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HomeMy WebLinkAbout052124 SUPPLEMENTAL CORRESPONDENCE - IN OPPOSITION Flashman Stuart 052024 attachmentsLaw Offices of Stuart M. Flashman 5626 Ocean View Drive Oakland, CA 94618-1533 (510) 652-5373 (voice & FAX) e-mail: stu@stuflash.com 20 May 2024 Danville Town Council 50 La Gonda Way Danville, CA 94526 Re: Appeal of Parks, Recreation & Arts Commission Decision on Osage Station Park Pickleball Courts Expansion Project. Dear Mayor Stepper and Councilmembers: I represent the appellant in the above -referenced appeal. When this project first came before the Commission, more than a year ago, the Commission planned to approve it without any analysis of its environmental impacts under CEQA — the California Environmental Quality Act. The Commission apparently felt it would be exempt from CEQA as a minor alteration to existing facilities. I wrote to the commission and pointed out that pickleball play produces far more noise than the tennis courts that would be replaced. Given the site's proximity to neighboring residents, a noise analysis was needed. Also, given the popularity of pickleball and the closeness of the park to a school, traffic and pedestrian/bicyclist safety impacts also needed to be examined. The Commission backed off. It prepared a Negative Declaration under CEQA. It then approved both the negative declaration and a revised Project. The approval granted by the Commission would expand the existing two pickleball courts to eight — a four -fold increase. As noted, the Commission approved the project based on a Negative Declaration — meaning that the Town was asserting with certainty that there would be no significant impacts. It did this in spite of receiving substantial evidence showing that the expansion would likely cause significant noise, traffic, and pedestrian safety impacts Now, the Town has apparently decided that, contrary to its consultants' original and later revised analyses, the added pickleball courts would have the potential to result in significant noise impacts. As a consequence, the Town has now circulated a Mitigated Negative Declaration ("MND"). The MND, and the accompanying report from the Town's same acoustic consultant, now assert that the added mitigation measures will reduce noise impacts to a level of insignificance. It's important to understand when a negative declaration, or a mitigated negative declaration, is appropriate, and when it isn't. A negative declaration states that, with certainty, the project could not have any significant impacts on the environment. For a mitigated negative declaration, the basic principle is the same. The difference is that, while the project might potentially result in a significant impact, feasible mitigation measures will, again with certainty, reduce the impacts to a level of insignificance. In either case, If there is any substantial evidence — meaning facts, reasonable assumptions predicated on facts, or expert opinion supported by facts, not just speculation (CEQA Guidelines Section 15384) — that would support a fair argument that Danville Town Council — Appeal of Parks, Recreation & Arts Commission approval of Osage Station Park Pickleball Court Expansion Project. 5/20/24 Page 2 the project could have a significant impact, neither a Negative Declaration nor a MND is appropriate. Put simply, for a MND, if substantial evidence indicates that the mitigation measure might not be feasible, or might not reduce the impact to a level of insignificance, the MND must be rejected. It doesn't matter how much evidence the Town has supporting the MND. Nor does it matter whether the Town has tried "in good faith" to evaluate the impacts. Because both types of negative declarations require certainty, there can be no reasonable possibility of the final project having a significant impact! That is a very stringent standard for the Town to meet; and at the moment the Town's mitigated negative declaration doesn't come close to meeting that standard of certainty. I. NOISE IMPACTS Both the Town's initial negative declaration and its new MND are based almost entirely on studies prepared by its consultants.' The noise consultant was Rincon Consultants ("Rincon"), a statewide firm providing a wide variety of services.2 For the mitigated negative declaration, the study's author is identified and his credentials are provided. Rincon's report for the mitigated negative declaration now concedes that the four -fold expansion of pickleball courts at Osage Station Park could result in significant noise impacts. The report goes on to assert, however, that placing "sound blankets" on three of the four fences surrounding the courts, to a height of 12 feet, along with other measures, will eliminate the objectionable, annoying, and intrusive noise impacts.3 There are several problems with Rincon's analysis and its results. These are pointed out in the attached letter from Dr. R. Lance Willis, an acoustics consultant that I have retained. Dr, Willis has also provided earlier letters to the Town pointing up deficiencies in the Town's acoustic consultant's analyses. Those letters are incorporated herein by reference. I am also attaching a report that Dr. Willis prepared for the City of Centennial, Colorado, to guide its evaluation of pickleball court proposals. (Hereinafter referred to as "Centennial".) That report provides a lot of basic information about noise, both in general and the noise generated during pickleball play. As you will see from that report, Dr.Willis has spent much time studying pickleball noise generation and its mitigation. That knowledge informs the comments in his letter. What are the problems Dr. Willis has identified? 1 There were also many supportive comment letters from pickleball enthusiasts. However, such expressions of argument, speculation, unsubstantiated opinion or narrative do not constitute substantial evidence. 2 See: https://www.rinconconsultants.com/ (accessed 1/30/2024). 3 The Town's noise ordinance specifically prohibits annoying noise. (Section 4-2.3(a).) Noise annoyance is considered a significant impact under CEQA. (Berkeley Keep Jets Over the Bay Com. v. Board of Port Cmrs. (2001) 91 Cal.App.4th 1344, 1380-1382.) Danville Town Council — Appeal of Parks, Recreation & Arts Commission approval of Osage Station Park Pickleball Court Expansion Project. 5/20/24 Page 3 First, while at least some of Rincon's measurements were made using the "fast" setting on Rincon's sound meter (125 ms time constant4), that setting is still far too slow to accurately measure the maximum sound levels produced by pickleball racket impacts. Those impact noises last only a very short 5 ms. 5 As a result of the meter's inappropriate averaging of sound levels over time, the sound meter's measurements, even on its "fast" setting, significantly underestimated the sound levels that the ears of nearby residents would be subjected to. Rincon reduced the maximum noise standard by five decibels to account for the impulsive nature of the impact noise. However, as the attached letter from Dr. Willis, and his prior letters to the Town, explain, that still does not fully take into account the annoyance effect of the noise produced from the multiple simultaneous pickleball games that can be expected under the Project.6 Under the internationally recognized ANSI standard (S12.9, Part 4) for controlling highly impulsive noise impacts, a 12 dBA reduction is recommended due to the high annoyance effect of such highly impulsive noises. (Centennial at p. 21.) Thus Rincon's latest analysis still significantly underestimates the noise annoyance impact of the project. Further, all of Rincon's noise measurements were made "at least five feet above the ground." Presumably, this was intended to simulate what the noise level would be for a person at ground level. However, no measurements were made at higher elevations that would simulate the sound heard in a second -story bedroom of one of the surrounding houses. Nor, as Dr. Willis' letter point out, are any three-dimensional geometric measurements provided on the distances between the proposed pickleball courts and the surrounding fencing and between the fencing and the second -story bedrooms of the surrounding residences. (See attached photos of some of those houses.)' A basic principle of sound propagation is that sound waves (like light waves) travel primarily in straight lines. Thus, to block sound, one must also block the line of sight between the sound generator and the sound receptor. (Centennial at p. 50.) Without the three-dimensional distance information, it is impossible to accurately estimate how much sound will be blocked by the proposed "sound blanket" mitigation a i.e., the meter averages the loudness over a 125 ms time period. 5 The human ear can detect noises lasting for as little as 2 ms. (https://biology.stackexchange.com/questions/27662/what-is-the-human-ears-temporal-resolution (accessed 5/16/2024) 6 See also, attached copy of the 2005 version of the ANSI impulsive noise standard, as referenced in Dr. Willis' letters. It should be noted that the current version of the standard has removed the word "enumerated" from the definition of highly impulsive sound (Section 3.41 on page 3) thereby broadening the range of included sounds so it is not limited to the listed sounds, but also includes other sounds of a similar nature — such as pickleball racket impacts. (Due to copyright restrictions, the current ANSI standards are only available under a paid license.) The most sensitive place for an indoor receptor would be a house's bedrooms. In a two-story house, like many of those neighboring Osage Station Park, bedrooms are typically located on the second floor. Danville Town Council — Appeal of Parks, Recreation & Arts Commission approval of Osage Station Park Pickleball Court Expansion Project. 5/20/24 Page 4 and how much will reach the surrounding houses, and specifically their second -floor bedrooms. There are additional problems with the proposed "sound blankets" being proposed as mitigation. As explained more fully in Dr. Willis' letter, according to the sales brochures for the AcoustiFence "blankets" being proposed, they are plain mass - loaded vinyl fence covers. The brochure emphasizes that the AcoustiFence blankets will absorb, rather than reflect, low -frequency noise (<50 Hz). However, pickleball racket impact noise is not low frequency. Rather, its noise peaks in the range of 1-2 kHz. At that frequency, as the brochure's graph indicates, the AcoustiFence panels will efficiently reflect the pickleball racket impact noise rather than absorb it. Not only will this increase the noise to which pickleball players and spectators will be exposed, but the reflected noise will "echo" back and forth in the east -west direction, add to the noise going above the fence and into the bedrooms of neighboring houses. In short, the Town has not shown that the proposed "sound blanket" mitigation will, with certainty, reduce the noise annoyance impacts to a level of insignificance. Quite to the contrary. It may even further increase annoyance noise levels in nearby houses. Dr. Willis' letter also explains other ways in which the AcoustiFence barriers will be problematic. As additional mitigation, the Town proposes to provide signage requiring the use of "Quiet Category" rackets. However, it proposes no enforcement mechanism for that requirement. Nor does the Town's consultant letter provide any evidence about how much such rackets would reduce noise levels. Without that information, and an effective enforcement mechanism, such a requirement may be close to meaningless. It is certainly not a meaningful and enforceable mitigation measure. Finally, while the Town commits itself to hiring an acoustical consultant to measure post -mitigation noise levels at adjoining residential property lines, to ensure they do not exceed applicable noise thresholds (including an appropriate adjustment for impulsive noise), it does not explain what will happen if those measurements indicate that the noise levels with proposed mitigation measures still exceed the thresholds. No fail-safe "back-up" mitigation measures are identified that will ensure compliance. Without feasible and effective backup measures to ensure that the noise standards (including the adjustment for highly impulsive noise) are met, compliance has not been ensured. In short, the MND fails to show with certainty that no significant noise impacts will result from the Project with mitigation. 8 II. TRANSPORTATION AND PUBLIC SAFETY IMPACTS As to transportation impacts, the Town's transportation consultant, Kimley»Horn ("Kimley"), is a nationwide general consulting firm.9 Like Rincon, it provides a wide 8 USA Pickleball, the national group promoting pickleball, has recognized the noise problems of pickleball play and is currently funding research on mitigating the sport's noise impacts. (See attached copy of a recent article from the Bay Area News Group.) However, the results of that research are not yet final and validated, nor will they necessarily adequately mitigate noise from this proposed eight -court facility. 9 https://www.kimley-horn.com/ (accessed 1/30/2024). Danville Town Council — Appeal of Parks, Recreation & Arts Commission approval of Osage Station Park Pickleball Court Expansion Project. 5/20/24 Page 5 variety of consulting services. The firm's Pleasanton, CA office prepared a report on potential transportation impacts. That report also claims to be based on in-depth study and to provide unassailable conclusions, In reality, it likewise fails to provide the support needed to approve the project based on even a mitigated negative declaration. (No mitigation is proposed for potential transportation impacts.) Like the Rincon report, the Kimley study made questionable assumptions. Most significantly, it assumed the trip generation rate for pickleball court use could be based on the ITE Trip Generation Manual rate for tennis courts. (Kimley Report at p.9.) That number was adjusted by a factor of 1.5 to account for pickleball always being a doubles game while the tennis court rate was based on mixed singles and doubles play. However, no evidence was presented to validate use of the tennis court rate. In fact, the Town is being pressured by pickleball fans to quadruple the number of courts. It's also common knowledge that pickleball has become wildly popular with groups, such as those over age 40, that are not major tennis court users. These facts strongly suggest that using the tennis court trip generation rate greatly underestimated the trip generation rate to be expected for pickleball court use. Further, the concentration of eight courts at one park would make Osage Station Park stand out for pickleball enthusiasts, not only in the local Danville area, but throughout the Trivalley Area. That would make the project a subregional, rather than a purely local traffic magnet. That, in turn, means that Kimley's assumption that trips generated by the new pickleball will be very short is not only unsupported by evidence, but almost certainly grossly in error. To the contrary, the project will almost certainly significantly increase vehicle miles traveled from the current average, a significant transportation impact. The Kimley Report also assumed that the trip generation rate was constant throughout the day. It did not consider that pickleball players (other than retirees) would be likely to schedule their games for after work — resulting in higher trip rates during the PM peak hour. Also, the Kimley Report did not provide evidence to validate any of its assumptions, making their use highly questionable. It should also be noted that, even using the "lowballed" assumptions of the report, projected traffic volumes for the eight -court option were barely below the roadway capacity for Orange Blossom Way south of the park — a significant increase over current traffic. (Kimley Report, p. 11.) Not only does this indicate congestion and a significant increase in vehicle miles traveled, but such congested conditions tend to lead to increased rates of pedestrian and bicyclist accidents. The Kimley report did not discuss pedestrian or bicyclist safety at all! In short, the Kimley report was inadequate and does not support the Town's conclusion of no possibility of a significant transportation (or pedestrian/bicyclist safety) impacts. Danville Town Council — Appeal of Parks, Recreation & Arts Commission approval of Osage Station Park Pickleball Court Expansion Project. 5/20/24 Page 6 CONCLUSION The evidence presented by the Town's consultants indicating the project, as mitigated, would have no significant impacts does not support approving the project under a MND. Consequently, both the MND and the Project approval need to be rejected and my client's appeal should be granted. The Council therefore needs to reject the approval recommendation for the Project from the Parks, Recreation and Arts Commission and remand consideration of the project to the Commission with direction to either drop the project or reconsider it in light of the evidence presented showing that it may still have significant impacts. If (as seems highly likely) adequate mitigation cannot be fully assured, an Environmental Impact Report (EIR) should be prepared, circulated, and certified before giving further consideration to approving the project. The EIR must include consideration of both mitigation measures and project alternatives (including the option of spreading the pickleball courts over multiple sites). Most Sincerely, Stuart M. Flashman, Ph.D., J.D. Danville Town Council — Appeal of Parks, Recreation & Arts Commission approval of Osage Station Park Pickleball Court Expansion Project. 5/20/24 Page 7 ATTACHMENTS A. Letter from Dr. R. Lance Willis B. Report by Dr. Willis prepared for City of Centennial, Colorado C. ANSI Standard S12.9 Part 4 (2005) D. Bay Area News Group Pickleball Article (2/2/2024) E. Photos of homes neighboring proposed pickleball court project Attachment A Spendiarian & Willis Acoustics & Noise Control LLC The Form and Function of Sound (520} 523-6003 AcousticalNoise.com 4335 N Alvemon Way, Tucson, AZ 85718 Monday, May 20, 2024 Stuart Flashman Law Offices of Stuart Flashman 5626 Ocean View Drive Oakland, CA 94618 Dear Dr. Flashman, The latest revision of the noise study prepared by Rincon Consultants [Carman 2024] recommending noise mitigation for pickleball courts at Osage Park continues to contain errors in noise assessment methodology and mitigation design. These errors have been discussed in previous letters from this firm [Willis 2023, 2024]. Rincon, however, continues to use the Leq and Lmax metrics that have no relevance to the noise -induced annoyance caused by highly impulsive sound generated by impact processes such as a pickleball paddle striking a ball. Code Requirements The Danville Noise Ordinance mentions "annoyance" twice. 4-2.1 Findings and Declaration of Intent. The Town Council finds that at certain levels noises are detrimental to the health and welfare of the citizenry and should be regulated in the public interest. It is the policy of the Town that the peace, health, safety and welfare of the citizens of Danville require protection from excessive, unnecessary, annoying and unreasonable noises from any and all controllable noise sources. 4-2.3 General Noise Regulations. (a) It is unlawful for a person to willfully make a loud, unnecessary or unusual noise which disturbs the peace or quiet of a neighborhood or which causes discomfort or annoyance to a reasonable person of normal sensitiveness residing in the area. Neither the equivalent -continuous sound pressure level (Leq) or maximum fast exponential time weighted sound pressure level (Lmax) are measures of annoyance for impulsive sound produced by impact processes. In a previous letter [Willis 2024 p. 1-3] it was explained in detail why Lmax cannot and should never be used to assess the noise -induced annoyance of impulsive sound. In short, Lmax is a rough approximation of loudness level only; however, annoyance of impulsive sound is strongly influenced by onset rate, or rise time. This is not disputed as stated in Spendiarian & Willis Acoustics & Noise Control LLC May 20, 2024 1 of 8 the recent Rincon report [Carman 2024 p. 3], "The impact of noise is not a function of loudness alone." Yet the noise study is based on Lmax which is an approximation of loudness level alone and Leq which cannot detect impulsive sound in the presence of background noise due to averaging over the entire time of the measurement. Human hearing does not average time variant sound in this way. In addition, Lmax does not consider the number of occurrences of a sound, only the single highest value. A noise impact assessment that accounts for noise -induced annoyance as required by the Danville Noise Ordinance has to date not been performed for the proposed pickleball courts at Osage Park. To meet this requirement the noise -induced annoyance of the sound from the paddle impacts must be assessed according to modern standards and best practices for this purpose such as ANSI S12.9 Part 4 [Willis 2024 p. 3-4]. Noise Mitigation Noise Barriers The recommendations for noise mitigation of the proposed pickleball courts in the latest Rincon report is to install a sound insulating fence cover on three sides of the courts. ...affix sound blankets of a minimum 12 -foot height to the chain-link fences enclosing the courts along the project southern, western, and eastern court boundaries. The sound blankets shall be at least 1/8 -inch thick, continuous from grade to top of the blankets with no gaps, and have a minimum sound transmission class (STC) rating of 28. [Carman 2024 p. 10] This is confusing on a number of counts. First, Rincon has gone from a finding that no noise mitigation is needed [Carman 2023] to recommending that the existing fence be removed and replaced with a taller fence to accommodate the 12 foot noise barrier using essentially the same analysis techniques as the original report. If the 12 foot fence cover was recommended to ensure there are no sight lines to the players on the courts and provide adequate shielding for the upper level windows and raised decks of the adjacent two story homes then this would make sense. There is, however, no indication in the study that this analysis was done. It is therefore not clear how the 12 foot noise barrier height was decided on. In fact, there does not appear to be any noise barrier calculations at all, just an assumption of a 10 dB insertion loss that will be discussed below, and no computations of the extents of the shielding provided for homes to the northwest of the proposed pickleball courts. Spendiarian & Willis Acoustics & Noise Control LLC May 20, 2024 2 of 8 The second issue is the term "sound blanket." A sound blanket is a quilted panel that absorbs sound and may or may not also have a mass -loaded vinyl (MLV) core to improve its sound insulating performance as well, i.e. prevent sound from going through the blanket. Although Rincon uses the term "blanket," the description of the material and the AcoustiFence brochure included in the appendix of their report indicate that the fence cover is in fact not a sound absorbing blanket, but a plain MLV fence cover. These are very different acoustical treatments. MLV is a reflective material at the most prominent frequencies produced by pickleball paddles near 1,000 Hz. The Sound Absorption Test Results chart in the AcoustiFence brochure [Carman 2024 p. 23] indicates the sound absorption coefficient at 1,000 Hz is about 0.05, very reflective. The reason this is important is that Rincon has specified MLV fence covers on three sides of the courts. That is, the east and west MLV panels will be facing each other trapping sound between them. Since there is nothing to dissipate this acoustical energy much of it will go over the top of the fence cover, severely degrading the performance of the noise barrier. This is not an appropriate configuration for this type of material. At a minimum the interior surface of the east fence needs to sound absorbing. Figure 1 shows an example of what can happen with a sound source located between two noise barriers. The red vertical lines are two 10 foot high noise barriers. Between them are a distribution of sound sources 4 feet above the ground marked by red asterisks. This simulation includes reflections up to 40th order from both interior surfaces. The four curves represent the sound pressure level with no barriers in place, a sound absorbing blanket noise barrier (AudioSeal), a freestanding wall system with integrated sound absorption of the type commonly used along roadways (Carsonite), and a reflective MLV fence cover. It can be seen from the figure that the performance of the MLV fence cover is significantly worse than either of the sound absorbing noise barriers and becomes continually worse as the distance from the sound sources increases. This is because the parallel reflective surfaces have the effect of increasing the number of sound sources. That is, a reflection creates an image source that is a time delayed copy of the original sound source. The more reflections that are allowed to occur between the barrier surfaces, the more images sources will be created. While the STC 28 rating (sound transmission class) of the MLV fence cover is sufficient be an effective noise barrier for pickleball, the above example demonstrates that it cannot be used alone without sound absorption in an application that incorporates noise barriers on opposite sides of a sound source. The MLV fence cover noise barriers recommended by Rincon will not perform in the way that they are expecting due to the uncontrolled reflections between the east and west fences. Spendiarian & Willis Acoustics & Noise Control LLC May 20, 2024 3 of 8 70 - - 30 0 m L� - 20 ** — No harrier — Seal _, Carsonite — MW Sound Pressure Level (dB ) 50 - 40 –400 –300 –200 –100 0 100 200 Position (ft) Figure 1. Example of Facing Reflective and Absorbing Noise Barriers - 10 0 A further concern is that there is no evidence of any insertion loss calculation, the difference in sound pressure level before and after the mitigation treatment is installed, for the fence cover noise barrier. There is only this comment in the study. With implementation of the recommended mitigation measure, project operational noise would be conservatively reduced by at least 10 dBA. [Carman 2024 p. 10] Spendiarian & Willis Acoustics & Noise Control LLC May 20, 2024 4 of 8 In light of the above discussion it should be evident that this is not a conservative estimate and that the actual insertion loss will likely be significantly less than this with MLV fence covers installed as recommended by Rincon. There is also no analysis of the sound going around the noise barrier on the exposed north side of the pickleball courts. Figure 2 shows a sight line from a property line 200 feet from the northwest corner of the courts pad. Mitigation is normally required at 200 feet from pickleball courts; however, this property has direct line of sight to several of the proposed pickleball courts. In addition, the reflective fence cover will further exacerbate the situation by reflecting sound from the southern row of courts where it too will spill out through the open north fence. Osage Par Pickle Ball Figure 2. Sight Line to Open North End of Pickleball Courts Spendiarian & Willis Acoustics & Noise Control LLC May 20, 2024 5 of 8 The Rincon noise study has not looked at the shielding coverage of the fence cover, including flanking paths, in any detail. There is also no evidence of any analysis of the sound reaching the upper level windows and raised decks of the adjacent homes. Equipment Policy Rincon recommends the use of quiet equipment as a noise mitigation measure. Prior to project operation, post signs at the pickleball court entrances with a list of allowable USA Pickleball "Quiet Category" -compliant paddles. Non -quiet paddles shall be prohibited. [Carman 2024 p. 10] Unless the Town has a formal plan with dedicated personnel and resources to monitor the courts and enforce this policy, it cannot be considered a noise mitigation measure. As this type of policy is unmanageable in most parks, the noise abatement plan should be designed around the equipment that pickleball players prefer to use and are most likely to bring to the courts. Postinstallation Acoustical Testing Following project implementation, the Town shall retain a qualified acoustical consultant to measure project operational noise levels to verify that noise levels at the closest residential property lines do not exceed the Town's thresholds. [Carman 2024 p. 10] This is prudent; however, repeating the type of noise impact assessment performed to date for this site will serve no purpose. The Danville Noise Ordinance requires an assessment of noise - induced annoyance. This requires using a test procedure and assessment methodology created for that purpose such as ANSI S12.9 Part 4. Conclusions A noise impact assessment that accounts for noise -induced annoyance as required by the Danville Noise Ordinance has not been performed for the proposed pickleball courts at Osage Park. To meet this requirement the noise -induced annoyance of the sound from the paddle impacts must be assessed according to modern standards and best practices for this purpose such as ANSI S12.9 Part 4. The primary objectionable sound source on pickleball courts is the impulsive sound produced by the impact of the ball on the paddles. The annoyance of this component of the sound has not been Spendiarian & Willis Acoustics & Noise Control LLC May 20, 2024 6 of 8 analyzed or assessed in any of the the Rincon noise impact assessments. The true noise impact of the proposed pickleball courts on the surrounding neighborhoods and amount of mitigation needed remains unknown; however, deficiencies and missing coverage in the proposed mitigation plan have been identified. In addition to the issues with the noise assessment and determining the amount of mitigation required, several design flaws were found in the recommendations for the fence cover. The recommendation of a reflective MLV fence cover is an inappropriate use of materials in applications involving noise barrier surfaces that face each other or where sound can be trapped and funneled around the ends of the barrier. Sound absorbing panels will be needed to control these reflections and dissipate acoustical energy that collects between the fence covers. There is no evidence that an analysis of the flanking path around the north end of the fence cover has been performed. Nor is there an assessment of the sound reaching the upper level windows and raised decks of the adjacent homes. There is no documented calculation for the minimum height of the noise barrier or for the extent of shielding coverage for homes north of the proposed pickleball courts that have a sight line onto the courts through the open north fence. Restrictions on the type of equipment used on the pickleball courts should not be considered a noise abatement measure if there is no plan and resources dedicated to monitoring and enforcing this policy. Spendiarian & Willis continues to find the noise impact assessment of the proposed pickleball courts at Osage Park to be insufficient for the reasons outlined in this letter. The Town's negative declaration of environmental significance is based on a noise impact assessment that does not include assessment of the noise -induced annoyance of the pickleball paddles and a noise abatement plan that will not perform in the way proposed by Rincon Consultants. This project is not ready to proceed. regards, R. Lance Willis, PhD Principle Acoustical Engineer Spendiarian & Willis Acoustics & Noise Control LLC May 20, 2024 7 of 8 References ANSI S12.9-2021, Quantities and Procedures for Description and Measurement of Environmental Sound — Part 4: Noise Assessment and Prediction of Long Term Community Response, American National Standards Institute, 2021. Available from <https://webstore.ansi.org/standards/asa/asaansis122021part> Carman, Josh, Noise Study for the Osage Park Pickleball Project, Danville, California, Rincon Consultants, Oakland, California, September 8, 2023. Carman, Josh, Noise Study for the Osage Park Pickleball Project, Danville, California, Rincon Consultants, Oakland, California, April 15, 2024. ISO 1996-1, Acoustics - Description, measurement and assessment of environmental noise - Part 1: Basic quantities and assessment procedures, International Organization for Standardization (ISO), 2016. Willis, R. Lance, letter to Stuart Flashman, Spendiarian & Willis, December 12, 2023. Willis, R. Lance, letter to Stuart Flashman, Spendiarian & Willis, January 17, 2024. Spendiarian & Willis Acoustics & Noise Control LLC May 20, 2024 8 of 8 Attachment B Spendiarian & Willis Acoustics & Noise Control LLC The Form and Function of Sound (520) 623-6003 AcousticalNoise.com 4335 N Alvernon Way, Tucson, AZ 85718 Pickleball Noise Impact Assessment and Abatement Planning Prepared for City of Centennial 13133 E. Arapahoe Road Centennial, Colorado 80112 Project Manager Neil Marciniak Lance Willis, PhD © Spendiarian & Willis Acoustics & Noise Control LLC R. 0, July 11, 2023 Spendiarian & Willis Acoustics & Noise Control LLC 1 of 77 Executive Summary As pickleball grows in popularity across North America it has become necessary to define more accurate methods of assessing the noise impact of the sport on the surrounding community and plan effective strategies for integrating it into various recreational venues. The purpose of this document is to provide descriptions of measurement protocols appropriate for assessing short duration impulsive sound such as pickleball and paddle impacts, definitions of terms and acoustical metrics, and guidance for acoustical planning of new pickleball courts. Basic methodologies and best practices for community noise assessment, environmental acoustics measurements, and noise regulation documents are described. The main concern for neighbors living close to pickleball courts is the popping sound produced by the paddle when it strikes the ball. This sound is narrowband, imparting a sensation of pitch, and very short in duration. For the latter reason, measurement techniques that involve averaging the sound pressure over time tend to underestimate the noise impact of the impulsive sound produced by the paddles. For this type of sound, the noise assessment methodology described in ANSI S12.9 Part 4 for the highly impulsive classification of sound, based on adjusted sound exposure level, is recommended as the most accurate means of assessing the community response to pickleball paddle impacts. Planning open air pickleball courts begins with selecting an appropriate site that has sufficient setbacks to ensure an effective noise abatement plan will be possible. Most of the work of reducing sound levels at the neighbors is done by noise barriers in the form of sound walls or mass -loaded vinyl (MLV) fence covers. These are, however, limited in the amount of noise reduction they can provide making setbacks a critical component for success of the overall noise abatement plan. In order for a noise barrier to provide acoustical shielding it must be able to block the line of sight from the players on the pickleball courts to the surrounding noise sensitive areas including upper level windows and raised decks. These geometrical considerations, which will include topography as well as the neighboring structures themselves, may affect the minimum setbacks needed in a particular application. Spendiarian & Willis Acoustics & Noise Control LLC 2 of 77 Table of Contents 1. Introduction 7 1.1 Pickleball and Pickleball Sound 7 1.2 Properties of Sound 8 1.3 Annoyance 8 1.4 Physiological Effects of Sound 9 1.5 Long Term and Short Term Community Impact 10 2. Definitions 12 3. Noise Regulation Best Practices 15 3.1 Purpose 15 3.2 Measurement Procedures 16 3.3 Common Ordinance Noise Descriptors 16 3.4 Reducing Vagueness 17 3.5 Current Standards in Noise Regulation 17 3.5.1 European Union Directive 2002/49 17 4. Classification of Environmental Sound 18 4.1 Amplitude Characteristics 18 4.1.1 Sound Pressure 18 4.1.2 Broadband Continuous Sound 19 4.2 Spectral Characteristics 20 4.2.1 Broadband 20 4.2.2 Narrowband 20 4.2.3 Tonal 20 4.2.4 Infrasound and Ultrasound 20 4.3 Temporal Characteristics 20 4.3.1 Stationary or Continuous 20 4.3.2 Impulsive 21 Highly Impulsive 21 High Energy Impulsive 21 Regular Impulsive 21 Modulated 22 4.3.3 Time of Occurrence 22 4.4 Ensemble and Background Sound Pressure Levels 22 5. Measurement and Assessment of Environmental Sound 23 5.1 Quantification of Sound 23 5.1.1 Sound Pressure 23 5.1.2 Frequency Weighting 23 5.1.3 Equivalent -continuous Sound Pressure Level 25 5.1.4 Day Night Level 25 5.1.5 Percentiles 26 5.1.6 Sound Exposure Level 26 5.1.7 Peak Sound Pressure Level 26 Spendiarian & Willis Acoustics & Noise Control LLC 3 of 77 5.2 Acoustical Instrumentation 26 5.2.1 The Sound Level Meter 26 5.2.2 Exponential Time Weighting 27 5.2.3 Integrating Sound Level Meters 27 5.2.4 Frequency Band Analysis 27 5.2.5 Calibration 27 5.3 Calculation Methods 28 5.3.1 Decibel Addition 28 5.3.2 Background Noise Correction 29 5.4 Measurement Procedures 30 5.4.1 Field Calibration 30 5.4.2 Measurement Conditions 31 5.4.3 Measurement Locations 31 5.4.4 Sound Level Meter Placement 31 5.4.5 One Hour Equivalent -continuous Sound Pressure Level Measurements 31 5.5 Adjusted Sound Pressure Levels 32 5.5.1 Assessing Tonal Sounds 32 5.5.2 Assessing Impulsive Sounds 32 5.5.3 Applying Adjustments Using Sound Exposure Level 32 5.5.4 Time of Day Adjustments 34 5.6 Measurement Reports 34 5.7 Noise Impact Assessments 35 5.7.1 Purpose and Methods 35 5.7.2 Present and Future Noise Exposure 35 5.8 Existing Noise Regulations 35 5.8.1 City of Centennial Municipal Code, Chapter 10, Article 12 35 5.8.2 Colorado Revised Statues 25-12-101 36 6. Characteristics of Pickleball Sound 38 6.1 Comparison of Pickleball to Other Activities 38 6.2 Effects of Impulsive Sound 40 6.3 Acoustical Characteristics 40 6.4 Directivity of Pickleball Courts 43 6.5 Noise Impact of Speech 44 7. Influence of Environmental Factors 46 7.1 Number and Arrangement of Pickleball Courts 46 7.2 Topography 50 7.2.1 Sight Lines 50 7.2.2 Noise Sensitive Locations Above Ground Level 50 7.3 Ground 52 7.3.1 Attenuation 52 7.3.2 Refraction 53 7.3.3 Valleys 53 7.3.4 Water 53 7.4 Reflective Surfaces 53 8. Noise Assessment Procedures for Pickleball Sound 55 Spendiarian & Willis Acoustics & Noise Control LLC 4 of 77 8.1 Inaccuracies of Simple Averaging Techniques 55 8.1.1 Equivalent -continuous Sound Pressure Level 55 8.1.2 Exponential Time Weighting 55 8.1.3 Percentile Sound Pressure Levels 57 8.2 Best Practices for Assessment of Impulsive Sound 58 8.3 Measurement Procedures for Highly Impulsive Sound 59 8.3.1 Measuring the Paddle Impacts 59 8.3.2 Measuring Background Levels 59 8.3.3 Data Analysis 60 Sound Exposure Level 60 Background Noise Correction 60 Adjusted Sound Pressure Level 60 8.4 Noise Assessment of Spectator Speech 60 8.5 Site Simulation 61 8.5.1 Modeling Distributed Sound Sources 61 8.5.2 Pickleball Court Directivity 63 9. Noise Abatement Methods 65 9.1 Setbacks 65 9.2 Noise Barriers 65 9.2.1 Performance Requirements 65 9.2.2 Fence Cover Safety Notice 66 9.2.3 Parallel Surfaces 66 9.2.4 Lowering Pickleball Courts 67 9.2.5 Ventilation and Air Flow 68 9.3 Court Orientation 68 9.4 Sound Masking 68 9.4.1 Masking Requirements 68 9.4.2 Roadways 69 9.4.3 Fountains 69 9.5 Full Enclosure of Pickleball Courts 69 9.6 Noise Control Policy 70 9.6.1 Hours of Operation 70 9.6.2 Restrict Players Allowed to Use Courts 70 9.6.3 Speech 70 9.6.4 Restrictions on Equipment 70 Quieter Equipment 70 Paddles 70 Foam Balls 71 10. Site Planning Considerations for Pickleball 72 10.1 When a Noise Impact Assessment Is Needed 72 10.2 Site Selection 72 10.2.1 Available Setbacks 72 10.2.2 Proximity to Multi -story Residential Structures 72 10.2.3 Topography 72 10.3 Tournaments 73 Spendiarian & Willis Acoustics & Noise Control LLC 5 of 77 11. Conclusions 74 11.1 Best Practices in Noise Assessment and Regulation 74 11.2 Characteristics of Pickleball Sound 74 11.3 Noise Impact Assessment of Pickleball 74 11.4 Noise Abatement Planning 74 11.5 Site Planning 75 References 76 Table of Figures Figure 1.1. Pickleball Game 7 Figure 4.1. Sound Pressure Levels of Some Common Sources 19 Figure 5.1. ISO 226 Equal Loudness Contours 24 Figure 5.2. ANSI S1.4-2014 Frequency Weighting Curves 25 Figure 5.3. Decibel Addition 28 Figure 5.4. Background Noise Correction 30 Figure 6.1. Pickleball Paddle and Ball Impact Sound Pressure Trace 41 Figure 6.2. Spectral Response of a Sharp Hit 42 Figure 6.3. Spectral Response of a Dull Hit 43 Figure 6.4. Typical Pickleball Court Directivity in Decibels 44 Figure 7.1. Adjusted Sound Pressure Level from Four Pickleball Courts 47 Figure 7.2. Adjusted Sound Pressure Level from Eight Pickleball Courts Aligned Longitudinally 48 Figure 7.3. Adjusted Sound Pressure Level from Eight Pickleball Courts Aligned Laterally 49 Figure 7.4. Adjusted Sound Pressure Level Contours, Four Courts, 10 Foot Wall, 5 Foot Elevation 51 Figure 7.5. Adjusted Sound Pressure Level Contours, Four Courts, 10 Foot Wall, 15 Foot Elevation 52 Figure 8.1. Fast Time Averaging Filter Response to a 0.277 Second Sound Burst 56 Figure 8.2. Fast Time Averaging Filter Response to a Typical Pickleball Paddle Impact 57 Figure 8.3. Pickleball Court Dimensions 62 Figure 8.4. Sound Pressure Level at Distance from Court Center for One and Two Sources 63 Figure 9.1. Performance Comparison of Interior Parallel Surfaces of Noise Barriers 67 Figure 9.2. Sound Wall Overlap 68 Index of Tables Table 1.1. Application of Short and Long Term Noise Regulation 11 Table 8.1. Pickleball Court Directivity Pattern 64 Spendiarian & Willis Acoustics & Noise Control LLC 6 of 77 1. Introduction 1.1 Pickleball and Pickleball Sound Pickleball is popular and rapidly growing paddle sport in the United States and Canada. It is played with a hard plastic ball similar to a wiffle ball. A pickleball court is 44 feet long and 20 feet wide compared to a tennis court at 78 feet long and 36 feet wide. A tennis court can be converted into four pickleball courts. r ia`u r i 9iw NAVNigniK%r ■wrw ourA AMA, Ie; e" ar .Jd 1 hilt -rrrrr r rtf ■k p. f r rrrr i �S 1...14+11 PAPPIPI Figure 1.1. Pickleball Game As the sport has grown so have concerns from those living near pickleball courts over noise. The impact of the pickleball on the paddle causes a sharp popping sound that can be heard hundreds Spendiarian & Willis Acoustics & Noise Control LLC 7 of 77 of feet from the courts. Unfortunately, poor siting and inadequate noise impact assessment and abatement at many locations have made open air pickleball courts controversial additions in many neighborhood settings. This document will provide guidance on noise impact assessment in general, how to accurately measure the sound produced by pickleball courts, site selection, and effective mitigation treatments. 1.2 Properties of Sound Sound, for the purposes of the this document, is a small pressure disturbance in the atmosphere producing the sensation of hearing. It may be produced by the vibration of a surface or by the pulsation of an airstream such as a rotating fan blade or the human vocal cords. Sound propagates through the atmosphere as a compression wave with a speed that increases with the temperature of the air. The characteristics of a particular sound are described in terms of amplitude (loudness), frequency (pitch), and the change of amplitude and frequency with time (impulsiveness, modulation, onset rate, or rise time). Noise is unwanted sound. This may be a subjective assessment or it may imply effects on health, well being, and speech communication. Community noise impact is assessed in terms of both annoyance and public safety. 1.3 Annoyance The subjective aspect of noise is known as "annoyance." Annoyance describes the quality of a sound that is perceived as objectionable. It differs from loudness, the perceived amplitude of a sound. Annoyance is often influenced by nonacoustic factors such as habituation or sensitization to the sound, involvement in activities that require concentration, attitudes towards sound sources and their operators, and the perceived necessity of the noise intrusions. For these reasons, reports of annoyance will have varying degrees of response bias. Annoyance as a basis for determining acceptable noise levels can be traced to a paper by T. J. Schultz [Schultz, 1978] and the work of other researchers in the 1960's and 1970's. Schultz aggregated a group of social surveys regarding transportation noise in different cities and found that the results could be explained using a noise dosage relationship. This method has since been adopted by federal agencies tasked with regulating and evaluating road, rail, and air transportation noise. Early research into the community impact of noise focused mainly on road traffic noise. As a result, other sound sources studied later were compared to traffic noise impact studies to determine their level noise impact. It was found that the sound pressure levels of sound sources having special characteristics such as impulsiveness and tonality did not correlate well with community questionnaires when directly compared to traffic sound pressure levels. The annoyance of these sources was often higher than the traffic noise for the same sound pressure level. For this reason, the sound pressure levels of sound sources having these special characteristics are given an adjustment to compensate for the difference in noise impact. Part 4 of the ANSI S12.9 standard gives adjustments and measurement methodologies for a variety of sound Spendiarian & Willis Acoustics & Noise Control LLC 8 of 77 classifications and is used as the basis for the sound pressure level adjustments in this document. 1.4 Physiological Effects of Sound While it is well known that high amplitude acoustical pressures can cause hearing impairment as well as other types injury to the body, lower amplitude sound can also have adverse long term physiological effects. The World Health Organization recognizes that low level noise exposure has measurable health effects: Sound/noise is a psychosocial stressor that activates the sympathetic and endocrine system. Acute noise effects do not only occur at high sound levels in occupational settings, but also at relatively low environmental sound levels when, more importantly, intended activities such as concentration, relaxation or sleep are disturbed. [WHO, Night Noise Guidelines, p. 61] The sympathetic nervous system is part of the autonomic nervous system and is involved in the body's fight or flight arousal response. Chronic activation of the sympathetic system leads to stress, fatigue, and anxiety. In addition to nervous system activation, sleep disturbance from noise can involve difficulty in falling asleep as well as awakenings that occur during sleep. Frequent awakenings lead to sleep fragmentation. This disrupts the normal stages of sleep and may lead to further neurocognitive manifestations not limited to daytime tiredness, loss of concentration, morning confusion, irritability, anxiety, and depression. [WHO, Night Noise Guidelines, p. 48, 26] Environmental noise also has implications for the cardiovascular system, metabolism, and homeostasis, the ability of the body to regulate itself. The auditory system is continuously analyzing acoustic information, which is filtered and interpreted by different cortical and subcortical brain structures. The limbic system, including the hippocampus and the amygdala, plays an important role in the emotional processing pathways. It has a close connection to the hypothalamus that controls the autonomic nervous system and the hormonal balance of the body. Laboratory studies found changes in blood flow, [blood pressure] and heart rate in reaction to noise stimuli as well as increases in the release of stress hormones... Acoustic stimulation may act as an unspecific stressor that arouses the autonomic nervous system and the endocrine system... The arousal of the sympathetic and endocrine system is associated with changes in the physiological functions and the metabolism of the organism, including [blood pressure], cardiac output, blood lipids (cholesterol, triglycerides, free fatty acids, phosphatides), carbohydrates (glucose), electrolytes (magnesium, calcium), blood clotting factors (thrombocyte, aggregation, blood viscosity, leukocyte count) and others. In the long term, functional changes and dysregulation may occur, thus increasing the risk of manifest diseases. [WHO, Night Noise Guidelines, p. 62-63] The effects of stress can take many forms as seen above. Low level noise exposure that disturbs Spendiarian & Willis Acoustics & Noise Control LLC 9 of 77 sleep and concentration are known to produce a range of diagnosable illnesses and disorders. 1.5 Long Term and Short Term Community Impact Community response to noise is different for short term and long term exposures. Short term impact refers to sounds that occur occasionally for a limited period of time, usually on an irregular basis, that are not part of the normal activities on a property. These types of sounds are generally addressed in the municipal code. Zoning or land use regulations focus on long term community noise impact. These sounds occur regularly over a period of time measured in weeks, months, or years and are usually part of the normal activities on a property. In most cases, however, this would not include construction activities as these are temporary and not a normal part of the usage of the site. Municipal code noise regulations and land use code noise regulations serve different purposes, but compliment each other to protect the community from excessive noise under differing circumstances. The land use code governs long term community noise exposure and is directed mainly to developers and commercial property owners. A municipal code applies to short term noise sources that generally do not operate on a regular basis. The table below shows a comparison of how these two codes work separately and together to provide a more complete community noise policy. Spendiarian & Willis Acoustics & Noise Control LLC 10 of 77 Table 1.1. Application of Short and Long Term Noise Regulation Spendiarian & Willis Acoustics & Noise Control LLC 11 of 77 Municipal Code Land Use Code Assessment Type: Short term noise impact Long term noise impact Directed Toward: Residents, public gatherings, noise control officers, police officers Developers, architects, acoustical engineers, planning & development dept., noise control officers Purpose: • Set threshold for offenses • Define penalties • Guidance for site planning • Standards for noise abatement • Long term noise assessment Main Area of Law: Criminal Civil Findings: • Made by officer on scene • Immediate determination of required action • Assessment of all sound sources affecting surrounding properties by acoustical engineer • Analysis presented in detailed report Expected Outcomes: • Immediate action • Possible cease and desist order, citation, or arrest • Comprehensive plan to bring the site into compliance • Installation of noise abatement treatments Spendiarian & Willis Acoustics & Noise Control LLC 11 of 77 2. Definitions A -weighted sound level A measurement of a sound level obtained using "A" frequency weighting. This weighting curve approximates the frequency response of human hearing for low to moderate sound pressure levels. The frequency weighting characteristics of the A -weighting filter are defined in ANSI S1.42 and ANSI S1.4. Background sound Sound from all existing sources near and far that may interfere with a sound pressure level measurement, not to include the sound source being evaluated. Decibel (dB) Ten times the logarithm to the base ten of the ratio of two quantities that are proportional to power. Quantities denoted as a "level" are decibel quantities, e.g. sound pressure level. Ensemble sound Sound from all normal existing sources near and far at a given location, including the sound source being evaluated. The union of all sound sources observable at the point of assessment. Equivalent -continuous sound pressure level The sound pressure level of a steady, continuous sound having the same sound energy as the time varying sound measured. Ten times the logarithm to the base ten of the time average over the period of a measurement of the square of the ratio of the sound pressure to the reference sound pressure of 20 micropascals expressed in decibels (dB). Fast exponential time weighting A lowpass filter for the purpose of averaging or smoothing a signal having a time constant of 0.125 seconds applied to the square of the sound pressure as specified in ANSI S1.4-1983. Highly impulsive sound Impulsive sound having very rapid onset rate or rise time typically resulting from impact processes or small arms gunfire including, but not limited to: metal hammering, wood hammering, drop hammering, pile driving, drop forging, pneumatic hammering, pickleball paddle and ball impacts, pavement breaking, metal impacts during rail -yard shunting operation, and riveting. ISO 1996 differentiates highly impulsive sound from regular impulsive sound by its noted level of intrusiveness. Spendiarian & Willis Acoustics & Noise Control LLC 12 of 77 Impulsive sound Sound that is characterized by brief excursions of sound pressure, typically less than one second, whose peak pressure noticeably exceeds the background sound pressure. Insertion loss (IL) For a sound attenuator, noise barrier, or other noise abatement treatment, the decrease in sound level at a point of observation when the noise abatement treatment is inserted between the sound source and point of observation. Noise Any sound which annoys or disturbs humans or which causes or tends to cause an adverse effect on humans, domesticated animals, or livestock. Noise abatement plan A detailed plan demonstrating the mitigation measures to be taken in order to meet the requirements of this noise regulation. The noise abatement plan should describe the construction and locations of abatement treatments with the expected sound pressure levels at the receiving properties. Noise impact assessment An analysis performed by a qualified acoustical engineer which determines the potential noise impacts of a proposed use. Peak sound pressure The largest absolute value of the instantaneous sound pressure in pascals (Pa) in a stated frequency band during a specified time interval. Regular impulsive sound Impulsive sound that is not highly impulsive sound. This includes speech and music. Sound exposure level (SEL) Sound exposure level is a descriptor for characterizing the sound from individual acoustical events. The sound exposure is the time integral of the square of the sound pressure over a time interval equal to or greater than an acoustical event having units of pascal squared seconds. The sound exposure level is ten times the logarithm to the base ten of the ratio of the sound exposure to the product of the square of the reference sound pressure of 20 micropascals and the reference time of one second expressed in decibels (dB). Sound level meter (SLM) An instrument used to measure sound pressure levels meeting the Type 1 standards for accuracy in ANSI S1.4-1983. Integrating sound level meters shall comply with ANSI S1.43-1997 Type 1. If octave band or fractional octave band filters are used, they shall comply with ANSI S1.11- 2004 Class 1. Spendiarian & Willis Acoustics & Noise Control LLC 13 of 77 Sound pressure A disturbance or perturbation of the atmospheric pressure with respect to the mean barometric pressure producing the sensation of hearing or vibration measured in units of pascal (Pa). Sound pressure level (SPL) 20 times the logarithm to the base 10 of the ratio of the sound pressure to the reference sound pressure of 20 micropascals (µPa) expressed in decibels (dB). Tonal sound Sound having one or more single frequency oscillations (pure tones) or that is confined to a narrow band of frequencies meeting the criteria for tonal prominence. See ANSI S12.9 Part 4 Annex C or ANSI S1.13 Annex A. Spendiarian & Willis Acoustics & Noise Control LLC 14 of 77 3. Noise Regulation Best Practices 3.1 Purpose A community is made up of individuals, families, businesses, government, land owners, tenants, and other groups conducting activities for their livelihoods and enjoyment. The purpose of noise regulation is to find a balance between the legitimate activities of one group and the need for peace and quiet of another and to provide a clear process for resolving disputes when they arise. Zoning noise regulations provide design goals for developers in planning a site for a specific activity and serve as criteria for assessing the community noise impact of existing sites. Clear guidance with regard to acceptable sound pressure levels is essential for ensuring new projects conform to community standards and for evaluating the compliance of existing land uses. Noise regulations should set clear and enforceable limits on community noise exposure that accurately reflect the community response to a variety of common sound sources. Overly strict regulations lead to arbitrary and selective enforcement while overly simplistic sound pressure level limits lead to the impact of certain classifications of sound being underestimated or ignored completely. A well provisioned noise regulation will therefore provide a comprehensive and accurate methodology for assessing the most common classifications of sound that impact a community. This ensures that community noise impact will be evaluated in a way that is representative of the experience of living and working in the community and also protects property owners from unreasonable demands for mitigation. Most importantly the noise regulations should provide a definitive means for bringing noise disputes to resolution. Key goals of noise regulation include: • Provide quantitative design targets for noise abatement • Provide protections for neighbors for all classifications of sound • Protect property owners from drawn out noise disputes Benefits of good noise regulation: • Defined design requirements for developers • Easier to get financing for projects due to lower risk and uncertainty • Enforceable standards for compliance • No cutting corners for contractor at risk Spendiarian & Willis Acoustics & Noise Control LLC 15 of 77 3.2 Measurement Procedures Noise regulation generally takes the form of specifying maximum allowable A -weighted sound pressure levels at a given location. It is important that the locations specified for assessment and compliance be accessible such as at a property boundary. Property boundary regulations protect the receiving property in its entirety against noise intrusions from adjacent sites. They also do not require entering private property in order to conduct acoustical testing. Performing acoustical measurements on the offending site creates bias due to the closer proximity to the sound source. Creating a noise abatement plan for new developments using noise assessment locations on the receiving property or inside a structure makes ensuring compliance more complicated. This will be discussed further in Section 3.3. 3.3 Common Ordinance Noise Descriptors Noise ordinances often do not have objective limits on sound pressure level, but instead use subjective criteria to evaluate noise impact. This leads to a great deal of difficulty in resolving noise disputes since neither side can agree on what the terms mean. One common term is "audible" or "plainly audible." The problem with this criterion is that neighbors will always be audible at certain times depending on meteorological conditions, time of day, etc. This places everyone in violation of the noise code leading to arbitrary and selective enforcement. The threshold of audibility depends on the background noise level at a specific location and time. It is therefore unpredictable for site planning purposes and unrepeatable. There is also no practical way to monitor without setting up a surveillance style recording system and reviewing the playback to identify the source in question. Another common ordinance criterion is "excessive, unnecessary or offensive noise which disturbs the peace or quiet of any neighborhood or which causes discomfort or annoyance to any reasonable person of normal sensitivity residing in the area." This regulation puts the arbiter in the position of deciding who is a reasonable person and what constitutes normal sensitivity. It turns an engineering problem of assessing noise impact based on decades on scientific field studies into a personal problem with no clear guidance on consistent application or how to reach resolution. The Maricopa County, Arizona Code, section P-23, prohibits sounds that can be "heard from within closed residential structures." This code is unenforceable because it is untestable. First, it requires access to a private home or place of business. The home or business must then be searched to verify that all doors and windows are closed. For a developer it is impossible to plan for or ensure compliance with such an ordinance because it is dependent on the construction of the receiving structures. The subjective criteria described above may be difficult to enforce due to vagueness. Under the vagueness doctrine a statute may be void if it leads to arbitrary enforcement, does not provide fair notice of what is and is not punishable, or does not detail the procedures followed by officers or judges of the law. Spendiarian & Willis Acoustics & Noise Control LLC 16 of 77 3.4 Reducing Vagueness The first step in reducing vagueness in noise regulation is to adopt a comprehensive, objective standard that addresses the most common sources of noise complaints, particularly impulsive and tonal sounds. There should be separate criteria for short and long term noise impacts. The zoning or land use code should focus on long term impacts while the municipal code addresses short term nuisance noise. The standards should not be overly restrictive such that common, everyday activities cause violations leading to arbitrary enforcement. Sounds that are subjectively negative and disturbing for contextual reasons may require enumeration and specific restrictions in addition to sound pressure level limits This may involve use limitation to certain times of day, complete prohibition, or other policies as deemed appropriate to the situation. A 5 to 10 dB adjustment for the enumerated sound sources may also be an effective means to address their greater noise impact. 3.5 Current Standards in Noise Regulation 3.5.1 European Union Directive 2002/49 The current, most up to date noise regulations with regard to scientific research have been enacted through European Union Directive 2002/49. This directive implements the noise assessment methodology in International Organization for Standardization standard ISO 1996. The American adaptation of ISO 1996 is ANSI S12.9 Part 4. These standards provide a comprehensive, objective method to assess the community noise impact of the most common sources of noise complaints including broadband continuous, impulsive, and tonal sounds. In addition to the assessment methodology, ANSI S 12.9 Part 5 provides guidance for acceptable day -night levels for a variety of land uses. In practice, setting sound pressure level limits for residential, commercial, and industrial zoning areas is usually sufficient. Spendiarian & Willis Acoustics & Noise Control LLC 17 of 77 4. Classification of Environmental Sound The impact of noise on a community is not always simply determined by the amplitude of the sound. Sounds that vary rapidly with time or have certain frequency characteristics can have an additional impact. This chapter discusses the classification of sounds with special characteristics and how they relate to community noise response. 4.1 Amplitude Characteristics 4.1.1 Sound Pressure The most fundamental characteristic of sound is its pressure amplitude measured in units of Pascals (Pa). Due to the extremely wide sensitivity range of human hearing, sound pressure is normally presented on a logarithmic scale known as the decibel scale and denoted by the symbol, dB. It is important to note that the decibel is a scale or unit of level, not a unit of measure. A decibel quantity must therefore have a reference value to define it. Any acoustic quantity described as a "level" is by definition on a decibel scale. The sound pressure level (SPL) is the sound pressure in Pascals normalized to the standard acoustical reference pressure of 20 10-6 Pascals as follows, SPL = 20 login P 1 20.10 6 where p is the sound pressure in Pascals and SPL is the sound pressure level in dB. Figure 4.1 shows some typical sound pressure levels of common sound sources. Sound pressure levels in the blue range are very quiet and usually found only in special environments such as anechoic test chambers or remote forest areas. The green range is typical of quiet environments. For outdoor sound, most daytime noise regulations begin to apply in the yellow range at starting 55 dBA. The U.S Department of Housing and Urban Development will require a noise abatement before funding residential projects above 65 dBA. Above 75 dBA they will require a stringent approval process. At 90 dBA in the workplace, OSHA will require a hearing protection program for workers. Spendiarian & Willis Acoustics & Noise Control LLC 18 of 77 Sidewalk next to busy highway Open elan office Living room I9.0 100 90 BO 70 60 50 40 30 20 10 u Indoor rock concert Speech at 3 feet Suburban neighborhood 1 Recording studio Sound Pressure Level {dBA) Figure 4.1. Sound Pressure Levels of Some Common Sources 4.1.2 Broadband Continuous Sound A sound pressure level reading that does not change rapidly with time, does not contain tones, and covers a wide frequency range is said to be broadband with respect to frequency and continuous with respect to time. Broadband continuous sounds are characterized primarily by their sound pressure level. Common examples are fans, well pumps, and traffic noise. Broadband continuous sounds are the simplest to quantify and are used as a point of comparison for other types of sound. That is, they provide a stable and relatively neutral basis for comparing tonal, impulsive, and other special sound classifications. The sound pressure level limits set in most noise regulations apply to this type of sound. Other sound classifications are adjusted so that their impact can be compared to a broadband continuous sound pressure level. This greatly simplifies noise regulations; however, it requires methodologies to be defined to accurately normalize sounds with special characteristics on the basis of community response to those characteristics. Spendiarian & Willis Acoustics & Noise Control LLC 19 of 77 4.2 Spectral Characteristics The spectrum of an acoustic wave refers to its frequency content. The frequency range that a sound occupies may cover a wide band of frequencies, only a very narrow band, or even a single frequency in the case of a tone. Frequency is measured in units of Hertz (Hz) which are equivalent to one cycle per second. 4.2.1 Broadband As described above, broadband means that the sound covers a broad spectrum of frequencies. This type of sound is in general the most neutral in terms of subjective sound quality. A broadband source with emphasis on the frequencies above 1,000 Hz may, however, be characterized as sharp or shrill. 4.2.2 Narrowband Sounds occupying only a narrow portion of the auditory spectrum are said to be narrowband. Narrowband can be regarded as having a bandwidth less than 1/3 of an octave. This type of sound is sometimes encountered in impact processes where the impact excites a structural resonance, but the duration of the sound is very short due to damping in the structure. Narrowband sounds will require a sound pressure level adjustment due to their spectral characteristics in relation to broadband continuous sounds if they have tonal prominence (see Section 5.5.1 Assessing Tonal Sounds). 4.2.3 Tonal Sounds containing pure tonal frequencies are usually produced by rotating machinery, but can also be electrically amplified signals such as those created by a backup alarm. Human hearing is sensitive to tones. Sounds having tonal prominence will require an adjustment in order to be compared to broadband continuous levels (see Section 5.5.1 Assessing Tonal Sounds). 4.2.4 Infrasound and Ultrasound The nominal range of human hearing is 20 Hz to 20,000 Hz. Sounds outside this range are referred to as infrasound if below 20 Hz and ultrasound if above 20,000 Hz. Objectionable infrasound can sometimes be generated by wind turbines or industrial sound sources. 4.3 Temporal Characteristics The way sound changes with time can have a significant influence on the noise impact. Accounting for these characteristics is important for accurately predicting community response. 4.3.1 Stationary or Continuous Sound that changes slowly in amplitude with time is known as continuous or in statistical terms, stationary. In practice, sounds that do not meet the criteria for impulsive, rapid onset, or modulated are considered continuous and do not require any sound pressure level adjustment for Spendiarian & Willis Acoustics & Noise Control LLC 20 of 77 their temporal characteristics. 4.3.2 Impulsive Impulsive sound is characterized by brief excursions of sound pressure whose peak pressure noticeably exceeds the continuous sound pressure. The duration of a single impulsive event is usually less than one second. Impulsive sounds often create annoyance because they are similar to sounds that contain important information about our environment such as a sound outside the house or a door closing. We are sensitive to these types of sounds because they alert us to events occurring nearby that we may need to respond to. Continuous false alarms make it difficult to relax, concentrate, or sleep soundly without disturbance. Many researchers have found that impulsive sound requires a level adjustment to properly account for the special characteristics and sensitivity to this class of sound [Buchta, Smoorenburg, Vos] and that listeners are able to differentiate between loudness and annoyance for sounds with temporal variance [Dittrich]. Impulsive sound is considered to have three subcategories: regular impulsive, highly impulsive, and high energy impulsive. Each of these categories has a different sound pressure level adjustment. Highly Impulsive Highly impulsive sound is characterized by a sudden onset and high degree of intrusiveness. This is common for impact processes and small arms fire. Highly impulsive sound in general has a duration too short to be accurately measured using maximum fast exponential time weighting. Impulses with a regular repetition rate greater than 20 Hertz may be perceived as tonal rather than impulsive and require a tonal level adjustment. Research has indicated that highly impulsive sound should receive a 12 to 13 dB adjustment [Buchta, Smoorenburg]. ANSI S12.9 Part 4 and ISO 1996 Part 1 recommend a 12 dB adjustment. High Energy Impulsive High energy impulsive sound is usually produced by explosive sources where the equivalent mass of dynamite exceeds 25 grams. Common sources are blasting or artillery fire. Sonic booms not produced by small arms fire are also included in this subcategory. High energy impulsive sound differs from highly impulsive sound mainly in the amount of low frequency energy produced. Regular Impulsive Impulsive sound not categorized as high energy or highly impulsive is categorized as regular impulsive. ANSI S12.9 Part 4 and ISO 1996 Part 1 recommend a 5 dB adjustment for regular impulsive sound. Spendiarian & Willis Acoustics & Noise Control LLC 21 of 77 Modulated Another type of transient sound is characterized by amplitude modulation. These sounds consist of a continuous series of impulsive events such as speech or music. Human hearing is most sensitive to amplitude modulation at a rate of about 4 Hz [Zwicker & Fastl, p. 177, 247-8]. This, not surprisingly, is the rate at which talkers typically produce syllables when speaking. Sounds having amplitude modulation near this rate may cause higher annoyance than continuous sounds at the same sound pressure level and should be treated as regular impulsive. When a large number of conversations is occurring at once such that the words of individual speakers cannot be understood, the noise impact may be more similar to a broadband continuous sound source. 4.3.3 Time of Occurrence Sounds that occur at certain times may become more objectionable. The community noise impact of sounds that occur at night is higher than in the daytime. Community noise impact is also higher during times when people are normally at home than when they are normally away at work. 4.4 Ensemble and Background Sound Pressure Levels Noise complaints usually involve a specific sound source. In any outdoor environment the source of interest will be among many background sources. Since it is in general not possible to remove the background sources, acoustical measurements must be performed in the presence of all active sound sources. "Ensemble sound pressure level" will refer to the sound produced by all sources at a given location including the source of interest. "Background sound pressure level" will refer to the sound present with the source of interest deactivated. Spendiarian & Willis Acoustics & Noise Control LLC 22 of 77 5. Measurement and Assessment of Environmental Sound 5.1 Quantification of Sound 5.1.1 Sound Pressure The measurement of sound in regard to noise regulation focuses on the sound pressure level (SPL) as described in Section 4.1.1. The human ear is a pressure sensor; therefore, the SPL most directly relates to the community response to noise. The human sensation of hearing does not, however, work in the same way that a microphone does. Spectral and temporal characteristics of a sound source can have a significant effect on the community response to that source. Signal processing must be applied to the measured sound pressure in order to adjust the measurement to the actual sensitivities of human hearing. 5.1.2 Frequency Weighting The first step in accurately representing the perceived loudness of sound is to simulate the frequency response of the human ear. Human hearing has lower sensitivity to sounds below 250 Hz and above 8,000 Hz as seen in Figure 5.1 [ISO 226]. Hearing sensitivity as a function of frequency is, however, also a function of amplitude. Different frequency weighting filters must therefore be used for different amplitude ranges. Figure 5.2 illustrates the A and C frequency weighting curves [ANSI S 1.4] that simulate the equal loudness contours of human hearing with respect a 1,000 Hz tone at sound pressure levels of 40 and 100 dB respectively. Noise regulations generally specify the A -weighted sound pressure level since this curve most closely matches the target noise level goal for broadband sound sources. A -weighted sound pressure levels are commonly expressed as dBA, dB(A), or LA. Spendiarian & Willis Acoustics & Noise Control LLC 23 of 77 Sound Pressure Level (dB) 130 120 110 100 90 BD 70 GO 50 40 30 20 10 4 -10 I I I 1 Frequency (Hz) Figure 5.1. ISO 226 Equal Loudness Contours Spendiarian & Willis Acoustics & Noise Control LLC 24 of 77 " -100 phon 80 60 40 20 0 (hearing threshold) I I I 1 Frequency (Hz) Figure 5.1. ISO 226 Equal Loudness Contours Spendiarian & Willis Acoustics & Noise Control LLC 24 of 77 Weighting Filter Gain (dB) 0 – 10 – 20 30 40 50 – 60 – 70 10 100 1000 Frequency (Hz} 10000 Figure 5.2. ANSI S1.4-2014 Frequency Weighting Curves 5.1.3 Equivalent -continuous Sound Pressure Level The equivalent -continuous sound pressure level is the principal acoustical quantity measured for long term noise impact assessment. This is a root -mean -squared average of the sound pressure over a period of time expressed as a sound pressure level. Equivalent sound pressure levels may represent the average level over a period of minutes, an hour, or some other interval. The A -weighted equivalent sound pressure level is represented as LAeq. The equivalent - continuous sound pressure level does not use exponential time weighting (see below). 5.1.4 Day Night Level A variation of the A -weighted equivalent sound pressure level is the day night level (DNL or Ld„). This metric incorporates the increased sensitivity to noise at night by adding a 10 dBA adjustment to sound occurring between 10:00 pm and 7:00 am. DNL is the most common metric used for transportation noise and is often applied to other broadband continuous sound sources. Spendiarian & Willis Acoustics & Noise Control LLC 25 of 77 - r� A. f r a ,�� ti - — A 10 100 1000 Frequency (Hz} 10000 Figure 5.2. ANSI S1.4-2014 Frequency Weighting Curves 5.1.3 Equivalent -continuous Sound Pressure Level The equivalent -continuous sound pressure level is the principal acoustical quantity measured for long term noise impact assessment. This is a root -mean -squared average of the sound pressure over a period of time expressed as a sound pressure level. Equivalent sound pressure levels may represent the average level over a period of minutes, an hour, or some other interval. The A -weighted equivalent sound pressure level is represented as LAeq. The equivalent - continuous sound pressure level does not use exponential time weighting (see below). 5.1.4 Day Night Level A variation of the A -weighted equivalent sound pressure level is the day night level (DNL or Ld„). This metric incorporates the increased sensitivity to noise at night by adding a 10 dBA adjustment to sound occurring between 10:00 pm and 7:00 am. DNL is the most common metric used for transportation noise and is often applied to other broadband continuous sound sources. Spendiarian & Willis Acoustics & Noise Control LLC 25 of 77 5.1.5 Percentiles To gain more insight into the noise environment during a long term measurement, some statistical quantities may be employed. The quantities LAIo and LA90 represent the A -weighted sound pressure level exceeded during 10% and 90% of the time of the measurement. LA90 is often used as an indication of the minimum background noise level without the presence of single noise events. LA10 indicates the highest sustained levels. 5.1.6 Sound Exposure Level The sound exposure level (SEL) is used to quantify single noise events. It is particularly useful when the duration of an impulsive sound is too short to be accurately measured with an equivalent -continuous or exponential time weighted sound pressure level measurement. The equivalent -continuous level represents the mean squared average sound pressure. It does not account for instantaneous peak pressures. Impulses with short durations tend to get averaged out although the peak pressure may be significant. This can sometimes lead to the mistaken conclusion that the impulse has no greater noise impact than the background noise. The sound exposure level also allows single noise events to be extracted from the measurement so that adjustments for special characteristics can be applied to more accurately represent the community response. 5.1.7 Peak Sound Pressure Level For impulsive sounds with rapid onset, the instantaneous peak sound pressure level may be important. This metric may be used to supplement the sound exposure level for highly impulsive noise events that do not occur frequently enough to accumulate a substantial amount of sound energy, but nevertheless do present a significant noise impact due to their high peak pressure levels. It should be noted that peak sound pressure level alone does not necessarily differentiate between intrusive highly impulsive and regular impulsive sounds. Different impulsive sound sources with the same peak sound pressure may have different noise impacts. Noise impact assessment of impulsive sound is often multidimensional involving onset rate, frequency range, and impulse duration. 5.2 Acoustical Instrumentation 5.2.1 The Sound Level Meter In the regulation of community noise, a sound level meter (SLM) meeting prescribed standards for accuracy and conformity is used. The meter consists of a microphone and a signal processing unit that performs frequency weighting (usually A and C) and time weighting functions. The sound pressure level is displayed on the meter. An SLM that can log sound pressure levels and compute an equivalent -continuous level is called an integrating SLM. Modern SLMs incorporate digital signal processing capable of logging many acoustical metrics at the same time and can save simultaneous calibrated audio recordings for source confirmation and further analysis. Spendiarian & Willis Acoustics & Noise Control LLC 26 of 77 Most professional acousticians use, and many noise regulations require, a meter meeting the ANSI S1.4 Type 1 standard. This is the highest accuracy used for field work. Type 2 meters meet a lower standard of accuracy and are allowed by OSHA and some municipal codes. 5.2.2 Exponential Time Weighting When taking sound pressure level measurements in the field, the reading on the meter can fluctuate rapidly for some sound sources. Exponential time weighting is a method of stabilizing the reading by applying a smoothing filter to the sound pressure envelop. Professional sound level meters will typically have three exponential time weighting settings: fast, slow, and impulse. The slow setting has time constant of 1 second. The fast setting time constant is 0.125 seconds (1/8 of a second). For most measurements the fast setting is preferred with the exception of impulsive sounds with a rapid onset rate. Impulse time weighting uses a 0.035 second time constant on the rise of the sound pressure envelop with a peak hold having a 1.5 second time constant on the decay. The purpose of this setting is to allow a faster response on the rise of the signal to reduce the attenuation of the maximum pressure of the impulse, but have a slow decay to hold the reading on the meter display so it can be read and recorded. This time weighting is, however, still much slower than the impulse produced by typical highly impulsive sound source such as a pickleball paddle impact. 5.2.3 Integrating Sound Level Meters Integrating SLMs integrate the sound pressure over the time period of a measurement in order to calculate the equivalent -continuous sound pressure level (LAeq). An integrating meter is required for noise regulations that specify metrics based on equivalent -continuous sound pressure level such as the day night level (DNL) or hourly sound pressure level. 5.2.4 Frequency Band Analysis Some sound level meters include filters for obtaining octave band and fractional octave band sound pressure levels. Frequency band data is needed for designing sound walls and other noise abatement treatments. Unweighted octave band sound pressure levels may also be used to assess low frequency sound in regard to acoustically induced vibration caused by air handling units or subwoofers. 5.2.5 Calibration The calibration of the sound level meter should be recertified by a qualified, independent metrology laboratory at intervals recommended by the manufacturer of the meter, usually one year. The sound level meter shall be used as provided in the manufacturer's instructions. It is standard practice when carrying out sound pressure level measurements to place a calibration device recommended by the meter manufacturer over the microphone before and after testing to verify that the sensitivity of the microphone has not changed and that the equipment has not been damaged prior to or during testing. The field calibrator should also be sent to a Spendiarian & Willis Acoustics & Noise Control LLC 27 of 77 qualified metrology laboratory to have the calibration certified at intervals specified by the equipment manufacturer. This period is usually one year. 5.3 Calculation Methods 5.3.1 Decibel Addition When working with multiple sound sources, it may be necessary to understand how each individual source contributes to the total sound pressure level. Decibel levels do not add arithmetically, but must be combined logarithmically. Figure 5.3 shows a chart for adding two levels. First, calculate the difference in the levels. Next, find the level difference on the horizontal axis of Figure 5.3 and find the corresponding level addition of the vertical axis. Add this number to the highest of the two levels. For example, to add two levels, 50 and 56 dB, together, find the difference, 6 dB, on the chart. The addition is 1 dB. Therefore, the decibel sum of 50 and 56 dB is 57 dB. If the level difference is greater than 10 dB, the contribution of the lower level source is negligible. •-- 2.5 m 2.0 • 1.5 i▪ l.0 < 0,5- 0.0 0 4 6 Difference in Levels (dB) Figure 5.3. Decibel Addition Equation 5.1 gives the direct calculation for the decibel sum, Ls, of levels, L1 and L2. Spendiarian & Willis Acoustics & Noise Control LLC 28 of 77 10 Ls=101ogio (100.1L1+10ofhL2) (5.1.1) 5.3.2 Background Noise Correction When assessing a noise issue it is common to measure the sound source of interest in the presence of other background sources. If the background noise level is within 10 dB of the ensemble noise level (see Section 4.4) a background noise correction should be applied to avoid overestimating the sound pressure level produced by the source of interest. The corrected source level, Lsource, is found by the decibel subtraction of the background noise level, Lbgn, from the ensemble level, Lens. LSource— lologlo(10 . —10 Lb° (5.2) The background corrected sound pressure level of the source can also be found using Figure 5.4. Subtract the background sound pressure level from the ensemble level. Find this level difference on the horizontal axis of the figure and locate the corresponding decibel value on the vertical axis. Subtract this number from the ensemble sound pressure level to get the background corrected level of the source. If the ensemble sound pressure level is within 3 dB of the background noise level, the source of interest is producing less sound pressure than the background sources and cannot be accurately assessed. When the conditions on the site prevent the background sound pressure level from being measured it should be noted in the measurement report. Spendiarian & Willis Acoustics & Noise Control LLC 29 of 77 Subtract from Ensemble Level (dB) 3.0 2.5 2.0 L5 1.0 0..5 0,t] 0 2 4 6 a Ensemble Level minas Background Level (dB) Figure 5.4. Background Noise Correction 10 Example: An exhaust fan located on the exterior wall of a warehouse building runs continuously. A sound pressure level measurement taken at the nearest residential property line with the fan running reads 64 dBA. The fan is then shut off and the measurement repeated. The sound pressure level now reads 58 dBA due to a nearby roadway. Subtracting the background noise level (58 dBA) from the ensemble level (64 dBA), which includes the fan and all other sound sources in the area, gives a difference of 6 dBA. From Figure 5.4, a 6 dB level difference on the horizontal axis corresponds to 1.0 dB on the vertical axis. Subtracting this number from the ensemble sound pressure level gives a result of 63 dBA for the sound pressure level of the exhaust fan by itself. 5.4 Measurement Procedures 5.4.1 Field Calibration The calibration of the sound level meter shall be recorded before and after each series of measurements using a field calibrator or method recommended by the manufacturer of the meter. Spendiarian & Willis Acoustics & Noise Control LLC 30 of 77 5.4.2 Measurement Conditions To the extent practical, all sound sources contributing to the ensemble sound pressure level at the point of measurement should be identified. Measurements should not be performed when wind speeds exceed 10 knots (11 miles per hour, 5 meters per second), the SLM may become wet, or temperatures are outside the tolerance range of the SLM as specified by the manufacturer. A properly fitted windscreen shall be attached to the microphone. Unless necessary, hourly or shorter duration measurements at distances greater than 100 feet (30 meters) should be performed on sunny days in order to avoid acoustic shadow zones formed by thermal inversions caused by ground heating. When the sun heats the ground, the relatively warm layer of air near the ground can cause sound to refract upward creating a complete or partial shadow. Measurements taken in the shadow zone can underestimate the sound pressure levels present at other times of the day. 5.4.3 Measurement Locations The preferred noise assessment location is at the property line of the receiving property at the point most impacted by the sound source in question. More than one measurement location may be necessary for multiple sound sources or some noise sensitive areas. In some situations the area most affected by the sound source of interest may be inside the boundaries of the receiving property. This is sometimes for the case, for example, if there is a wall blocking sound at the property line. Measuring the sound directly behind the wall may not be representative of the sound levels farther from the wall inside the receiving property or at the upper floors of a building located on the property. 5.4.4 Sound Level Meter Placement The microphone of the sound level meter should be placed at a minimum height of 45 inches (1.1 meters) above ground level and a minimum distance of 12 feet (3.6 meters) from any other reflecting surface. The microphone should not be placed closer than 12 feet (3.6 meters) from any sound source. Other microphone placements may be used as necessary to assess a specific noise sensitive area, but their acoustical characteristics must be specified. 5.4.5 One Hour Equivalent -continuous Sound Pressure Level Measurements One hour equivalent -continuous sound pressure level measurements shall be conducted using an integrating sound level meter. For sound sources that do not change in level over time, a shorter measurement period may be used provided the sound pressure level measured is typical of the source in question, but not less than 2 minutes. If a sound source has a regular operating cycle, the time period of the operating cycle, including both time on and time off, may be used for the measurement. Spendiarian & Willis Acoustics & Noise Control LLC 31 of 77 5.5 Adjusted Sound Pressure Levels Sound sources that have special characteristics including impulsiveness and tonality have been found to have a noise impact greater than that indicated by the equivalent -continuous level. To account for this a set of adjustments to the equivalent -continuous sound pressure level have been defined based on the recommendations of ANSI S12.9 Part 4. These adjustments apply to equivalent -continuous sound pressure level measurement such as one hour A -weighted sound pressure levels (LAeq) and octave band equivalent -continuous sound pressure levels. 5.5.1 Assessing Tonal Sounds Sounds having tonal prominence receive a 5 dB adjustment. Tonal prominence is determined according to ANSI S12.9 Part 4 Annex C by comparing adjacent unweighted one-third octave band equivalent -continuous sound pressure levels to the one-third octave band containing the tonal frequency. If the adjacent band level differences are greater than 15 dB for the 25 to 125 Hz bands, 8 db for the 160 to 400 Hz bands, or 5 dB for the 500 to 10,000 Hz bands, the tone has prominence and a tonal adjustment shall be applied to the one-third octave band containing the tonal component. Tonal prominence may also be determined using the narrowband methods in ANSI S1.13-2005 Annex A. This method may be necessary for tones that are close to the separation between two one-third octave bands resulting in bleed over into both bands. 5.5.2 Assessing Impulsive Sounds Two categories of impulsive sound are addressed in this document: regular impulsive and highly impulsive. Regular impulsive sound includes speech and music. It receives a 5 dB adjustment. Highly impulsive sounds receive a 12 dB adjustment. Highly impulsive sounds occurring at a rate greater than 20 per second are usually not perceived as distinct impulses and no impulse adjustment shall apply; however, if the repetitions are regular in time a tonal sound adjustment may be necessary. Equivalent -continuous sound pressure level alone is not sufficient to assess sounds characterized by impulsiveness. Highly impulsive and sporadic single events may produce a relatively small amount of energy compared to the background noise level. This does not necessarily mean they will not have a significant impact. Equivalent -continuous levels are often insensitive to short duration events even though the impulses may be clearly noticeable. In these instances the sound exposure method may be necessary to assess these events (see Section 5.5.3). 5.5.3 Applying Adjustments Using Sound Exposure Level Impulsive sounds are usually spread out in time whereas background noise is continuous. The background noise will therefore often contribute more to an energy averaging metric like the equivalent -continuous sound pressure level than the impulses even though an observer on the site may report the impulses as the primary sound source due to their high peak sound pressures. In Spendiarian & Willis Acoustics & Noise Control LLC 32 of 77 cases like this a windowing method such the sound exposure must be used to separate the impulses from the background noise so that adjustments can be appropriately applied to the part of the ensemble sound containing the impulses. One common use for the sound exposure level (SEL) is the comparison of two discrete sound events; however, in the context of applying adjustments to impulsive sound the SEL will be used to overcome the influence of the background noise by separating out the individual impulse events from the rest of the measurement data. The SEL of a single event, SELevent, can be found from the background noise corrected equivalent -continuous sound pressure level over just the time of the event, Leq,event, SEL event= Leq 'event + 101og10 ( TeventIT o ) (5.3) where Tevent is the duration of the event in seconds and To is the reference time of 1 second. Tevent should be inclusive of the entire event. In situations where the background noise level fluctuates it may be necessary to find the background noise level in the immediate vicinity of each impulse event in order to do the corrections. The appropriate regular or highly impulsive adjustment can now be added directly to the SEL of the event. This process can be repeated for each impulse to obtain a set of SELs. In order to compare the resulting sound exposures to the level limits in the regulations, the SELs must be converted to an equivalent -continuous level over the time period of the original measurement. The adjusted equivalent -continuous level of the impulses during the time of the measurement, Leq,adj, is therefore the decibel sum of each event's background corrected sound exposure level, SELevent,i, and its adjustment, K,, minus the measurement time, T, in decibels. Lea 3adj=E 1og1o(T/T0) (5.4) An alternative form of Eq. 5.4 is useful in when the mean SEL and the number of events over a period of time are known for an impulsive sound source. Leq,ad; = SEL sre+K impulse+ 101og 10 (N)iologio(T/T0) 0 (5.5) Here Leq,adj is equal to the sum of the sound exposure level for one event occurrence, SEL srej the adjustment for the type of impulse, Ki p,ise, the number of occurrences, N, in decibels, and total time period over which the impulses occur, T, in decibels. Leq,adj can now be combined with the other adjusted sound source levels in the project using Eq. Spendiarian & Willis Acoustics & Noise Control LLC 33 of 77 5.1 to obtain the total adjusted equivalent -continuous sound pressure level. This level can then compared to the level limits in the noise regulations. For more information on sound exposure level see ANSI S12.9 Part 4 and Harris, Chapter 12. 5.5.4 Time of Day Adjustments For noise impact assessment, the day is typically divided into three segments: day, evening, and night. For residential land uses, each of these time periods will have different noise sensitivities. During the daytime, usually defined as 7:00 am to 7:00 pm, many people are at work or busy with other activities away from home. In the evening, 7:00 pm to 10:00 pm, people tend to be at home and are more aware of noise in the area. Nighttime is the most noise sensitive time as people are sleeping. Weekends also have a higher noise sensitivity similar to evenings when people tend to be at home, but not sleeping. For residential land uses, time of day adjustments include a 5 dB adjustment for the evening and a 10 dB adjustment for the nighttime hours. Weekend daytime hours also receive a 5 dB adjustment similar to evening hours. 5.6 Measurement Reports After a set of field measurements have been completed, a report of the findings should be issued containing the following information: 1. Make, model, and serial number of each piece of measuring equipment 2. Date and location of the most recent laboratory calibrations 3. Site plan showing measurement locations 4. Statement of on-site calibration verification before and after each series of measurements 5. Name of the engineer conducting the tests For each measurement location the following information should be noted: 1. Date and time of the measurement 2. Acoustical metrics measured 3. Time and frequency weighting used 4. Microphone location and height 5. Windscreen used 6. Description of the test location including the type of ground and any reflecting surfaces near the SLM or sound source being investigated 7. Primary and secondary sound sources contributing to the measurement Spendiarian & Willis Acoustics & Noise Control LLC 34 of 77 8. Background noise level if investigating a specific sound source 9. Weather conditions: temperature, humidity, wind speed and direction, cloud cover, and sun exposure 10. Photo image showing the sound level meter and intervening ground between the meter and the sound source of interest 5.7 Noise Impact Assessments 5.7.1 Purpose and Methods A noise impact assessment provides a determination of the likely effects of introducing a new activity on the surrounding area. For new developments or modifications of existing developments involving on site activities that are likely to have a noise impact on the surrounding area, a noise impact assessment should be prepared by a qualified acoustical engineer. ISO 9613 and ANSI S12.62 provide a basic methodology for predictive acoustical site assessment; however, other methodologies may be used as appropriate for the area, conditions, and sound sources being evaluated. A noise impact assessment may be based on measurements of similar sound sources at a different location; however, differences in propagation paths that may affect the noise impact must be accounted for. 5.7.2 Present and Future Noise Exposure With many sound sources, the noise impact may increase over time, e.g. roadways and other modes of transportation whose usage can be expected to increase in the future. In preparing noise impact assessments for proposed developments, future usage patterns should be included in the analysis. 5.8 Existing Noise Regulations Best practices and current standards for noise assessment have been covered in Chapter 3. These criteria will be used here to evaluate noise regulations that apply within the City of Centennial. 5.8.1 City of Centennial Municipal Code, Chapter 10, Article 12 The City of Centennial does not currently have a land use noise regulation. Noise violations are defined in the Municipal Code. Two sections of the Code relate to noise assessment. Sec. 10-12-10. - Legislative declaration. It is hereby declared that protection and preservation of the home is of the highest importance; that unnecessary and excessive noise is a significant source of environmental pollution that threatens the public health, welfare, tranquility and good order of the community; and that the prohibitions and other protections set forth in this Article are enacted to secure and promote public peace, welfare, comfort and health. Spendiarian & Willis Acoustics & Noise Control LLC 35 of 77 Sec. 10-12-20. - General prohibition. It shall be unlawful for any person to make, continue or cause to be made or continued any excessive or unusually loud noise which: (1) Disturbs, annoys or endangers the peace, repose, comfort, safety or health of others; or (2) Endangers or injures personal or real property. These Code sections do not prescribe an objective measure of excessive noise, but state that "protection and preservation of the home is of the highest importance." Section 10-12-20(1) prohibits sound that "disturbs, annoys or endangers the peace, repose, comfort, safety or health of others." No guidance is given for compliance with the Code; however, ANSI S12.9 Part 4 is a standard for assessing annoyance in a community setting caused by noise and would be in alignment, as an objective assessment methodology, with the criteria in Section 10-12-20(1). 5.8.2 Colorado Revised Statues 25-12-101 The Colorado Revised Statues seeks to provide statewide minimum standards for noise levels. 25-12-101. Legislative declaration The general assembly finds and declares that noise is a major source of environmental pollution which represents a threat to the serenity and quality of life in the state of Colorado. Excess noise often has an adverse physiological and psychological effect on human beings, thus contributing to an economic loss to the community. Accordingly, it is the policy of the general assembly to establish statewide standards for noise level limits for various time periods and areas. Noise in excess of the limits provided in this article constitutes a public nuisance. C.R.S. 25-12-103(1) provides some objective maximum limits on permissible sound pressure levels. For residential land uses, the daytime limit is 55 dBA. Evening hours are not defined; however, nighttime hours are from 7:00 pm to 7:00 am. This includes hours that would normally be considered evening. The nighttime sound pressure level limit is 50 dBA which is more typical of a 5 dBA evening penalty than the more customary 10 dBA nighttime level limit reduction. Acoustical measurements are to be made 25 feet inside the receiving property boundary. This is problematic for a number of reasons. First, it requires entering private property in order to assess the sound level. This makes assessment, monitoring, and enforcement more difficult. It also does not protect the entire receiving property. This can be especially impactful for residents on small lots or rental properties where the back patio may be within this distance. While C.R.S. 25-12-103(3) does include provisions for impulsive sound, Periodic, impulsive, or shrill noises shall be considered a public nuisance when such noises are at a sound level of five db(A) less than those listed in subsection (1) of this section. with a 5 dBA reduction in the allowable sound pressure level, this approach is overly simplistic Spendiarian & Willis Acoustics & Noise Control LLC 36 of 77 and will underestimate the noise impact of highly impulsive sounds. Overall, the noise assessment procedure in C.R.S. 25-12 appears to be a compromise between simplicity of noise assessment and completeness. While adequate for many sound sources, it will underestimate the noise impact some classifications of sound that include highly impulsive sound and sounds that occur during regular nighttime hours of 10:pm to 7:00 am when most residents are sleeping. The choice of noise assessment location 25 feet inside the receiving property increases the difficulty of monitoring and decreases the level of protection afforded to home owners for the use of their outdoor spaces. Spendiarian & Willis Acoustics & Noise Control LLC 37 of 77 6. Characteristics of Pickleball Sound Spendiarian & Willis has prepared many noise assessments and abatement plans for pickleball courts. This chapter summarizes some of the knowledge gained over the years of working with this sound source. The main concern in regard to noise from the pickleball courts is the sound produced by the impact of the hard plastic ball on the paddles. This sound is characterized by a sudden onset and brief duration, thus classifying it as impulsive sound. The spectral content of the paddle impact is narrowband with a center frequency typically between 1,000 and 2,000 Hertz. This is near the most sensitive frequency range of human hearing. 6.1 Comparison of Pickleball to Other Activities There is a common misconception that pickleball is acoustically equivalent to tennis, volleyball, or many of the other activities typically found at outdoor recreation centers and parks. Numerous news articles covering disputes over pickleball noise, many of which originate when existing tennis courts are converted to pickleball, demonstrate that this is not the case: • Cutler, Amy, "Rise of pickleball pitting neighbor against neighbor, leading to lawsuits," Arizona's Family, Phoenix, Arizona. February 13, 2023. <https://www.azfamily.com/2023/02/ 13/rise-pickleball-pitting-neighbor-against- neighbor-leading-lawsuits/> • Arden, Amanda, "Lake Oswego shuts down city pickleball courts indefinitely due to noise complaints." KION 6 News, Portland, Oregon. January 23, 2023. <https://www.koin. com/local/lake-oswego-shuts-down-city-pickleball-courts- indefinitely-due-to-noise-complaints/> • Columbo, Mike, "Pickleball plan pits Kirkwood residents against neighboring country club." Fox 2 Now, Saint Louis, Missouri. January 26, 2023. <https://fox2now. com/news/contact-2/pickleball-plan-pits-kirkwood-residents-against- neighboring-country-club/> • Sheets, Connor, "Pickleball noise is fueling neighborhood drama from coast to coast." Los Angeles Times, Los Angeles, California. March 3, 2022. <https://www.latimes. com/california/story/2022-03 -03/pickleball-noise-fueling- neighborhood-drama> • Adler, Erin, "Apple Valley neighbors in a pickle over pickleball noise." Star Tribune, Minneapolis, Minnesota. March 27, 2019. <http://www.startribune.com/apple-valley- neighbors-in-a-pickle-over-pickleball-noise/507726242/> • Bartel, Mario, "Pickleball banished from Port Moody court after neighbours complain of Spendiarian & Willis Acoustics & Noise Control LLC 38 of 77 rising stress, anxiety." The Tri -City News, Coquitlam, British Columbia, Canada. April 24, 2021. <https://www.tricitynews.com/local-sports/these-games-are-loud-port-moody- pickleball-neighbours-revolt-against-rising-stress-anxiety-3 6623 69> • City of Lakewood, "Green Mountain Courts Closure." <https://www.lakewoodtogether.org/pickleball/news feed/green-mountain-courts- update> • Higgins, Sean, "No vote on residential pickleball until city adopts new land management code." KPCW News, Park City, Utah. January 27, 2022. <https://www.kpcw.org/park- city/2022-01-27/no-vote-on-residential-pickleball-until-city-adopts-new-land- management-code> • Maryniak, Paul, "Pickleball lights plan puts two HOAs at loggerheads." Ahwatukee Foothills News, Tempe, Arizona. November 29, 2017. <https://www.ahwatukee.com/news/article_9056a946-d48e-11 e7-9838- 8b69fb2d50b2.html> • Bottemiller, Kitty, "Too loud! Pickleball noise upsets neighbors." Green Valley News, Green Valley, Arizona. August 28, 2013. <https://www.gvnews.com/news/local/too-loud- pickleball-noise-upsets-neighbors/article_ 542c2aac-Of91-11 e3-acdc-0019bb2963f4.html> • Clay, Joanna, "Woman sues Newport Beach over pickleball noise at park near her home." Orange County Register, California. April 7, 2016. <https://www.ocregister. com/2016/04/07/woman-sues-newport-beach-over-pickleball- noise-at-park-near-her-home/> • Wheatley, Mike, "Noisy pickleball courts cause upset with homeowners." Realty Biz News. March 15, 2022. <https://realtybiznews.com/noisy-pickleball-courts-cause-upset- with-homeowners/98768719/#::text=In one lawsuit in Newport Beach%2C Calif.%2C a,are causing them less enjoyment of their home.> • Lazaruk, Susan, "Pickleballers face off with residents over noise in Metro Vancouver." Vancouver Sun, Toronto, Ontario, Canada. February 2, 2022. <https://vancouversun. com/news/local-news/pickleballers-face-off-with-residents-over- noise-in-metro-vancouver> • Shanes, Alexis, "Village in a pickle: How Ridgewood plans to tone down the pickleball court noise." northjersey.com, California. January 16, 2020. <https://www.northj ersey. com/story/news/bergen/ridgewood/2020/01 / 16/ridgewood-nj - pickleball-noise-reduction-measures/4480463 002/> • Monterey Herald Staff, "Pickleball noise controversy goes before city leaders Pacific Grove neighbors object to game at nearby tennis courts." The Mercury News, California. September 19, 2019. <https://www.mercurynews.com/2019/09/19/pickleball-noise- controversy-goes-before-city-leaders/> • Fraser, Patrick and Rodriguez, Ambar, "What to do about constant pickleball noise?" WSVN 7 News Miami, Miami, Florida. March 27, 2019. <https://wsvn.com/news/help- me-howard/what-to-do-about-constant-pickleball-noise/> Spendiarian & Willis Acoustics & Noise Control LLC 39 of 77 • Sutphin, Daniel, "Nixing the noise: Sound fence construction underway at Gilchrist pickleball courts." Port Charlotte Sun, Charlotte Harbor, Florida. May 20, 2019. <https://www.yoursun. com/charlotte/news/nixing-the-noise-sound-fence-construction- underway-at-gilchrist-pickleball/article_79a764de-7b 1 c-11 e9-b4d4-6bcaa919f3 f3.html> • Corrigan, James, "York residents complain noise from pickleball club is hurting quality of life." WMTW News 8, Portland, Maine. November 16, 2021. <https://www.wmtw.corn/article/york-residents-cornplain-noise-frorn-pickleball-club-is- hurting-quality-of-life/3 8271921 > It should be clear from the above list of references that pickleball constitutes a significant change in the acoustic environment of the area surrounding the courts in comparison to tennis and must be planned for accordingly. In particular, the impulsive sound produced by the impact of the hard plastic ball on the paddle can cause significant noise impact for those living near the courts. 6.2 Effects of Impulsive Sound Persistent impulsive sounds create annoyance because they are similar to sounds that contain important information about our environment such as footsteps, a door opening, a tap at the window, or speech. We are sensitive to these types of sounds because they alert us to events occurring nearby that we may need to respond to. Continuous false alarms such as the popping sound created by pickleball paddle impacts make it difficult to relax, concentrate, or sleep soundly without disturbance as each time a pop is heard it draws the attention, creating distraction. 6.3 Acoustical Characteristics The sound produced by the impact between a pickleball and paddle is characterized by a rapid onset and brief duration, typically on the order of 2 to 10 milliseconds (0.002 to 0.010 seconds) for the direct path sound. This classifies it as impulsive sound. Figure 6.1 shows a time trace of a pickleball paddle impact measured near Phoenix, Arizona. The main part of the direct sound impulse can be seen to be less than two milliseconds followed by a rapid decay and some later reverberant arrivals. Spendiarian & Willis Acoustics & Noise Control LLC 40 of 77 0.075 0.050 0- 0.025 - Ldrj o —0,025 v9 — 0,050 - — 0.075 - T 1 1 1 0 10 15 20 Time (ms) Figure 6.1. Pickleball Paddle and Ball Impact Sound Pressure Trace 1 millisecond (ms) = 0.001 seconds. The spectral content of the paddle impact is narrowband with a center frequency typically near 1,000 Hz (see Figure 6.2). Although it does not meet most guidelines for tonal prominence such as Annex C of ANSI S12.9 Part 4 or ANSI S1.13, it does impart a vague sensation of pitch similar to a wood block percussion musical instrument. The radiation pattern of the paddle is more or less a dipole, i.e. the sound from the front and back of the paddle is of opposite polarity and cancels itself in the plane of the paddle. Therefore, orienting the courts so that the direction of play faces away from noise sensitive areas can provide some attenuation. The sound power spectrum of the pickleball and paddle impact has two basic shapes depending on how the ball is hit. Figure 6.2 and Figure 6.3 show the power spectra of a 'sharp' hit and a 'dull' hit. The curves are not calibrated for absolute level, but can be compared relatively. The sharp hit spectrum shows a narrowband signature. The frequency of the peak typically varies between 1,000 and 2,000 Hz. The energy in the dull hit is more spread out, but still peaks between 1,000 and 2,000 Hz. Spendiarian & Willis Acoustics & Noise Control LLC 41 of 77 -oo -o5 -w -65 -m -75 -m -85 -vo -95 103 Frequency (H z) Figure 6.2. Spectral Response of a Sharp Hit Spendiarian &VViUiS Acoustics & Noise Control LLC 42 of 77 -50 -55 -50 -65 -70 -75 -80 -85 -90 -95 •100 103 102 frequency (H:) Figure 6.3. Spectral Response of a Dull Hit 10 A sound wall design will require effective attenuation in the 1,000 Hz octave band and above. In most applications, any material having a sound transmission class meeting STC 20 can be used to construct a sound wall or fence for pickleball provided best practices for sound barrier construction are followed. 6.4 Directivity of Pickleball Courts The impulsive sound of the paddle impacts is radiated mainly by the large, flat paddle surface. Since both faces of the paddle are connected internally by a honeycomb structure and move together in vibration, one side of the paddle will produce a positive sound pressure while the other produces a negative sound pressure similar to a loudspeaker diaphragm that is not mounted in a cabinet. The result is that these two pressure waves having opposite polarity will cancel in the plane of the paddle where the path length from each face is the same to all receiver locations. This is known as a dipole or figure eight radiation pattern. The positions of the paddles relative to the court change with each hit; however, the object of the game is to hit the ball to the opposite half of the court. Therefore, the dipole axis of each paddle impact will be in the general direction of play and not completely random. Measurements of Spendiarian & Willis Acoustics & Noise Control LLC 43 of 77 several pickleball facilities have shown that this results in a null depth of 4 to 5 dB. Figure 6.4 compares a typical pickleball court directivity pattern to a mathematical dipole where 0° and 180° are in the direction of play and the null is on the 90° and 270° bearings. Several decibels of attenuation can often be obtained simply by optimizing the orientation of the courts with respect to noise sensitive areas. 2700 -6 1 —g —12 --- Dipole Typical 180° 90° Figure 6.4. Typical Pickleball Court Directivity in Decibels 6.5 Noise Impact of Speech In addition to the paddle impacts, speech is also a sound source on pickleball courts. While there are standards for speech sound power levels at various degrees of vocal effort such as ANSI S3.5, sound from speech emitted from pickleball courts can vary greatly with who is playing on the courts at a given time and be difficult to predict. In practice, noise abatement treatments sufficient to mitigate the paddle impacts should also be sufficient for speech from the courts as the paddle impacts typically have a greater noise impact. Spendiarian & Willis Acoustics & Noise Control LLC 44 of 77 Most noise objections regarding speech on pickleball courts are related to the content of the speech rather than the loudness. While the sound level of the speech can be reduced through abatement treatments, it cannot be made inaudible in most situations. A noise impact of this type must be addressed through court usage policy. For tournament play, the overall speech pattern becomes more predictable. There are more sound sources that will approach a statistical average such as that described in ANSI S3.5. A total sound power level for the bleachers or spectator area can be calculated based on seating capacity or through direct measurement during a tournament. Spendiarian & Willis Acoustics & Noise Control LLC 45 of 77 7. Influence of Environmental Factors 7.1 Number and Arrangement of Pickleball Courts Pickleball courts are usually placed on a rectangular concrete pad approximately 30 by 60 feet. This is one quarter the size of a typical tennis court pad such that a tennis court can be converted into four pickleball courts. An important factor influencing the amount of sound reaching neighboring properties will be the number of pickleball courts. A doubling of the number of courts will result in a doubling of the number of sound sources and therefore the sound power emitted. This corresponds to a 3 dB increase in sound power level. Pickleball courts are, however, not a single sound source, but a distribution of many sound sources spread over the area of the courts. For this reason, sound radiated from pickleball courts will not follow the inverse square law unless the distance from the center of the courts to the point of observation is large compared to the dimensions of the court or group of courts. Figure 7.1 shows the ANSI S12.9 adjusted sound pressure level contours (see Section 8.3.3) at a height of 5 feet above grade for four courts, indicated by the red box, at the center of the main group of pickleball courts. For reference, the two groups of eight courts together have a width east to west of 136 feet and a length north to south of 268 feet. The oblong shape of the contours is not a result of the rectangular layout of the courts, but the directivity of the individual courts themselves (see Section 6.4). The 55 dBA contour extends about 480 feet from the courts in the direction of play and 260 feet laterally. Figure 7.2 expands the number of pickleball courts to eight arranged in pairs end to end. The 55 dBA contour extends about 630 feet from the courts in the direction of play and 350 feet laterally. Figure 7.3 rearranges the eight courts into two rows side by side. The 55 dBA contour extends about 685 feet from the courts in the direction of play and 340 feet laterally. Doubling the number of courts causes the 55 dBA contour to move out 30% to 40% of the distance from the courts pad (red boxes) depending on how the courts are arranged. The hypothetical examples above were created on level ground with a mixed ground type outside of the concrete pads for the courts (ISO 9613 ground factor, G = 0.5). In practice, noise complaints about pickleball courts at distances greater than 500 to 600 feet are rare. Real pickleball sites will usually have topographical features that hinder sound propagation at farther distances as well as structures that block or scatter sound. Pickleball courts across water may be an exception with the possibility of complaints occurring at distances approaching 800 to 1,000 feet. Spendiarian & Willis Acoustics & Noise Control LLC 46 of 77 Figure 7.1. Adjusted Sound Pressure Level from Four Pickleball Courts Spendiarian & Willis Acoustics & Noise Control LLC 47 of 77 Figure 7.2. Adjusted Sound Pressure Level from Eight Pickleball Courts Aligned Longitudinally Spendiarian & Willis Acoustics & Noise Control LLC 48 of 77 Figure 7.3. Adjusted Sound Pressure Level from Eight Pickleball Courts Aligned Laterally Spendiarian & Willis Acoustics & Noise Control LLC 49 of 77 7.2 Topography 7.2.1 Sight Lines In order for a noise barrier to be effective, it must block the line of sight from the sound source to the point of observation. Homes sitting at an elevation higher than the proposed pickleball courts can be difficult to shield, particularly if they have more than one floor, balconies, or raised decks. Attention must be given to sight lines to determine whether a sound wall system can be a practical solution as a noise abatement treatment. 7.2.2 Noise Sensitive Locations Above Ground Level In addition to elevation differences between the pickleball courts and surrounding properties, multistory housing can also result in sight line issues that lead to poor shielding. Figure 7.4 shows a mitigation example with four active pickleball courts in the southwest corner of the complex and a two story building to the south. A 10 foot sound wall (red line) has been placed along the south and west sides of the courts. The sound pressure level contours are at an elevation of 5 feet above grade. The 55 dBA contour does not reach the building. In Figure 7.5, the elevation of the sound pressure level contours has been raised to 15 feet above grade, about the height of a second floor bedroom window or a person standing on a second floor balcony or raised deck. The 55 dBA contour can now be seen to contact the building. This shows the importance of checking all floors of nearby structures to ensure that acoustical design targets are being met. It is important to note that, since the observation point on the second floor can overlook the sound wall, some paddle impacts will not be shielded. Although the partial shielding of the majority of the sound source locations is enough to lower the adjusted sound pressure level close to the target level of 55 dBA, peak sound pressures may not decrease as much as the adjusted level since some individual paddle impacts will not be shielded and may still have a significant noise impact. Spendiarian & Willis Acoustics & Noise Control LLC 50 of 77 Figure 7.4. Adjusted Sound Pressure Level Contours, Four Courts, 10 Foot Wall, 5 Foot Elevation Spendiarian & Willis Acoustics & Noise Control LLC 51 of 77 Figure 7.5. Adjusted Sound Pressure Level Contours, Four Courts, 10 Foot Wall, 15 Foot Elevation 7.3 Ground 7.3.1 Attenuation Some amount of attenuation can occur for sound passing over porous ground. This will mostly include friable soil with vegetation growing on it. Hard surfaces like concrete and asphalt are reflective. Painted concrete surfaces like sports courts are very reflective. Spendiarian & Willis Acoustics & Noise Control LLC 52 of 77 This should be considered when placing a noise barrier on a particular ground type. The barrier will block the ground wave and remove the ground effect. This will affect the performance of the noise barrier. Blocking the ground wave over hard ground will enhance the insertion loss, the difference in before and after sound levels, of the barrier while blocking the ground wave over absorbing ground may cause the insertion loss of the barrier to be less than expected. 7.3.2 Refraction Refraction caused by temperature gradients over certain ground can effectively cause sound to travel farther. Refraction is the bending of the path sound travels towards regions of lower sound speed, e.g. cooler air. This can be the result of temperature stratification of the atmosphere or wind. In low lying places where cool air tends to collect in the evenings or over irrigated ground where evaporative cooling can occur such as a golf course, a temperature lapse condition can develop with warm air above and cool air below. This will result in sound arcing down toward the ground. Refraction caused by a temperature lapse condition can result in sound arcing over obstacles on the ground that would normally impede its propagation thereby making it louder at farther distances. 7.3.3 Valleys Parks located at the bottom of a valley can pose a particular challenge as they tend to experience temperature stratification conditions regularly. Further, the sides of the valley may trap sound and send it echoing back to locations on the opposite side. Valleys often require a detailed propagation study to understand how sound moves through the area at different times of the day. 7.3.4 Water Bodies of water such as a pond or lake are a special type of ground that is highly reflective. It also tends to form a layer of cool air near its surface causing refraction effects similar to those described above. Sound propagation over water can be difficult to predict as its surface changes with wind and weather conditions. In calm conditions sound carries long distances over the surface of water. If a significant portion of the ground between a sound source and receiving property is water a detailed propagation study may be needed to determine the ground attenuation. 7.4 Reflective Surfaces Surfaces that reflect sound that are close to the pickleball courts can redirect sound in undesirable directions. These surfaces can be building facades, retaining walls, or even noise barriers. Mass -loaded vinyl (MLV) fence covers are particularly reflective and may not be appropriate in some applications. Unpainted masonry walls retain some porosity and will absorb a small small of sound, but should be considered reflective for the purposes of outdoor sound propagation. Reflected sound from a single surface may increase the total sound pressure level as much as 3 dB over the level of the sound coming directly from the source. (Due to the short duration of the impulse produced by a paddle impact and its short wavelength it is difficult to get the reflected Spendiarian & Willis Acoustics & Noise Control LLC 53 of 77 sound to sum coherently with the direct sound) The positions of noise barriers must be planned strategically to prevent sound from going in unwanted directions and creating a new noise issue. Parallel reflective surfaces can severely degrade the performance of a noise barrier. See Section 9.2.3 for more information on this design issue. Spendiarian & Willis Acoustics & Noise Control LLC 54 of 77 8. Noise Assessment Procedures for Pickleball Sound 8.1 Inaccuracies of Simple Averaging Techniques 8.1.1 Equivalent -continuous Sound Pressure Level The equivalent -continuous level (Leq) is a type of average sound pressure level over the entire period of a measurement. It represents a sound pressure level that has the same total energy as a measured sound pressure level that may vary over the time of the measurement. While the equivalent -continuous sound pressure level includes all acoustical events and background noise that occur during the time of a measurement, including short impulsive events such as pickleball paddle impacts, it only gives an indication of the average level. It is not strongly influenced by peak sound pressure levels. For example, four pickleball courts may produce 50 to 60 paddle impacts each minute. That is one impact about every second. Equivalent -continuous averaging will therefore spread the energy of each paddle impact over a period of about one second. The result is that the paddle impacts will usually be indistinguishable from the background noise due to their very short duration. This, however, will not be what is reported by observers near the courts. The main issue with using equivalent -continuous sound pressure level with pickleball is that it cannot be used to assess impulsive sound. This is the primary concern of neighbors living close to pickleball courts. A different metric that can account for the noise impact of the paddle impacts must be found. 8.1.2 Exponential Time Weighting Sound level meters will typically have two smoothing filters called fast and slow time weighting having time constants of 0.125 and 1.0 second respectively. These are first order lowpass filters applied to the square of the sound pressure and are known as exponential time weighting. Some meters will also have an impulse peak hold filter with a 35 millisecond time constant on the rise of the sound pressure level and a slow 1.5 second decay to assist in reading the maximum level. Fast exponential time weighting is often recommended for assessing impulsive sound. For highly impulsive sounds having short durations this metric does not work well. When the averaging time of the time weighting is longer than the duration of the impulse, the impulse is in the stopband of the lowpass filter. In other words, the time weighting is filtering out the impulsive sound source being measured. That is the purpose of a smoothing filter. Figure 8.1 demonstrates the filter response to a burst of sound just long enough to achieve a reasonably accurate reading within 0.5 dB of the true sound pressure level. The red curve represents the envelop of a burst of sound 0.277 seconds in duration. This is the time required for Spendiarian & Willis Acoustics & Noise Control LLC 55 of 77 1.0 0.8 - 0.6 - the output of the fast exponential time averaging filter (blue curve) to rise to within 0.5 dB of the actual sound pressure level of the sound burst. When the sound burst ends, the output of the exponential time averaging filter begins to decay. The peak value in the output of the fast exponential time averaging filter, after being converted to sound pressure level, is known as the Lmax level. Squared Sound Pressure Lmax - 1rnje = -0.5 dB - Sound burst Exponential time averaging — filter response 0.4 - 0.2 - 0.0 - 0.0 02 0.4 0.6 Time (seconds) 018 1 0 Figure 8.1. Fast Time Averaging Filter Response to a 0.277 Second Sound Burst Figure 8.1 shows the behavior of the fast exponential time averaging filter and Lmax when used properly. Figure 8.2 illustrates how the fast exponential time averaging filter responds to a typical pickleball paddle impact. Note that the time scale has been reduced for clarity. At the end of the 0.002 second impulse, the fast exponential time averaging filter has only had time to rise to a level that is 18 dB below the true sound pressure level of the impulse. The pickleball paddle impulse is so much shorter than the time constant of the averaging filter that the exponential Spendiarian & Willis Acoustics & Noise Control LLC 56 of 77 curvature of the filter response is not even visible. It is clear that fast exponential time weighting, much less slow exponential time weighting, cannot be used to assess the noise impact of pickleball paddle impacts. Squared Sound Pressure (Pa2) 1('- 0.8 0.6 0.4 - O. 0.0 - — Sound burst Exponential time averaging — biter response 0.000 0.002 0.004 0.006 Time (seconds) Figure 8.2. Fast Time Averaging Filter Response to a Typical Pickleball Paddle Impact 0.008 0.010 8.1.3 Percentile Sound Pressure Levels Another common method of analyzing sound pressure level over time is to rank the levels by the percentage of time that a given level is exceeded. Percentile sound pressure level is described in Section 5.1.5. For impulsive sound, percentile levels suffer from the issues of both equivalent - continuous and exponential time weighted levels. The majority of the energy in pickleball paddle impacts constitutes a very small percentage of the total measurement time. Even very low percentile levels like LA01, the sound pressure level Spendiarian & Willis Acoustics & Noise Control LLC 57 of 77 exceeded 1% of the time, are little influenced. Further, percentile levels are usually calculated from the fast exponential time weighted level, a metric that already strongly attenuates the short duration impulses of the paddle impacts. Like the previous averaging methods, percentile sound pressure levels do not distinguish paddle impacts well from background noise and correlate poorly with the community response to this type of sound source. 8.2 Best Practices for Assessment of Impulsive Sound Assessment of impulsive sound is multi -dimensional. In addition to loudness, other characteristics like onset rate, duration, and frequency range need to be considered as well to gauge the true noise impact. Due to the short duration of paddle impacts, averaging sound pressure level metrics such as equivalent -continuous level (LAeq), maximum fast exponential time weighted level (LAmax), and impulse time weighting (LAI) fail to accurately represent the perceived loudness and annoyance of the paddle impacts and impact processes in general. To get a better correlation with the actual response of the surrounding community to this type of sound metrics with a shorter time scale are needed. The paddle impact sound pressure level is better represented by a combination of peak sound pressure level and sound exposure level (SEL). Using the sound exposure level involves windowing the measured sound pressure in time to include only the paddle impact and reflections from nearby surfaces as seen in Figure 6.1. The equivalent -continuous sound pressure level of the windowed impact is then normalized to the length of the window giving a representation of the energy in the impact alone. Appropriate adjustments for impulsive sounds can then be applied to the impacts as described next. Most acoustical standards for sound pressure levels with regard to compatible land use provide adjustment factors for different types of sound, e.g. impulsive, tonal, time of day, etc. Each of these categories of sound produces different levels of community impact and annoyance due to their temporal or spectral characteristics in comparison to a broadband sound that does not vary in level or frequency content with time. The purpose of the adjustment factors is to normalize these types of sound to a neutral broadband sound pressure level so that they can be reasonably compared to a defined sound pressure level limit. ANSI S12.9 Part 4 and ISO 1996 Part 1 give criteria for assigning adjustment factors to a variety of sound classifications. Sounds produced by impact processes are typically classified as `highly impulsive' due to their high onset rates and intrusiveness and assigned a 12 dB adjustment. Experience has shown that pickleball paddle impacts should be adjusted as highly impulsive sounds in order to set appropriate performance goals for abatement treatments. Inadequate abatement treatment may lead to ongoing complaints, strained relations with neighbors, legal action, the need for continued involvement on the part of authorities, retrofitting, and possibly demolition costs to improve the abatement later. Spendiarian & Willis Acoustics & Noise Control LLC 58 of 77 8.3 Measurement Procedures for Highly Impulsive Sound 8.3.1 Measuring the Paddle Impacts General procedures for conducting and reporting acoustical measurements have been covered in Chapter 5. For pickleball, the sound level meter should be set up to record continuous audio. This will be needed for assessing the impulses produced by the paddle impacts. The audio should be written to an uncompressed file format such as WAV with the following properties. • Encoding: linear PCM WAV file format or other suitable lossless audio file format • Sampling rate: 48 kHz (minimum) • Resolution: 24 bit (minimum) Audio recordings of the field calibration tone should be made as well and the Leq noted for future reference. Logged data should be sampled at no more than one second intervals and include for each log interval, • Peak sound pressure levels • LApk (A -weighted peak level) • LZpk (unweighted peak level) • For speech assessment • LAmax (maximum A -weighted fast exponential time weighted level) • For background level • LAeq (A -weighted equivalent -continuous level) • LAF (A -weighted fast exponential time weighted level) • LAS (A -weighted slow exponential time weighted level) 8.3.2 Measuring Background Levels Background noise level measurements should be made without pickleball activity at each measurement location. In practice it has been found that background levels should be performed either before or after the pickleball courts are in use so as not to disrupt the rhythm of play by starting and stopping or otherwise interfering with the use of the courts. For noise monitoring situations where the sound level meter is left to run all day it may be necessary to find a time in the recorded data where the pickleball courts were not being used in order to assess the background noise level at different times of day. Spendiarian & Willis Acoustics & Noise Control LLC 59 of 77 8.3.3 Data Analysis Analysis of the measured data is performed on the sound exposure levels of the individual, A - weighted paddle impacts. A minimum of 30 paddle impacts should be obtained at each test location. Sound Exposure Level Some analysis and reporting software packages that work with a particular sound level meter may be able to do sound exposure analysis; however, they must be able to work on time scales less than one second. While the main part of the acoustical energy occurs within about a 10 millisecond window, later reflection and reverberation must also be included in the sound exposure window. The sound exposure should include all of the initial impulse and reverberant decay tail. See Sections 5.1.6 and 5.5.3 for more information on calculating sound exposure level. Background Noise Correction A background correction should be applied to each paddle impact. Since these are short impulses, only a small sample of the background noise immediately before, or if necessary after, the paddle impact is needed. This is will give a more accurate correction in areas of high activity where the background noise level is fluctuating between paddle impacts. The procedure for background noise correction is explained in Section 5.3.2. It should be carried out on the equivalent -continuous level of the individual paddle impact, not on the sound exposure level directly. The background corrected equivalent -continuous level of the paddle impact is then converted to a sound exposure level for further analysis. Adjusted Sound Pressure Level There are two adjustments that will normally apply to pickleball paddle impacts, highly impulsive and day of week. The highly impulsive adjustment is 12 dB. Noise assessment should be performed for the most impactful use case. A 5 dB adjust is therefore applied to account for the additional noise sensitivity during times when neighbors tend to be at home such as weekends and evenings. This brings the total adjustment to 17 dB. The adjustment can be applied directly to the calculated sound exposure levels. Now that the sound exposure levels have been adjusted, the adjusted sound pressure level can be calculated. This procedure is explained in Section 5.5.3. The adjusted sound pressure level can now be compared to applicable maximum permitted sound levels. 8.4 Noise Assessment of Spectator Speech For larger crowds of people such as found at a tournament, ANSI S3.5 provides standard speech power levels for different vocal efforts. The loud vocal effort may be most appropriate for most events. Spendiarian & Willis Acoustics & Noise Control LLC 60 of 77 Sound pressure level measurements of spectators at a tournament would be a better estimate where possible. Differences in the number of spectators present during the measurement and the number expected at the proposed venue should be taken into account. 8.5 Site Simulation An ISO 9613 or other suitable outdoor sound propagation standard can be used to calculate sound pressure levels at neighboring properties. Other more detailed environmental noise simulation methods exist and are also acceptable; however, ISO 9613 is simple and widely used with reasonable accuracy in most situations. There are many software packages available that implement this standard propagation model such as SoundPlan and iNoise. 8.5.1 Modeling Distributed Sound Sources Figure 8.3 shows the dimensions of a pickleball court. Most paddle impacts occur between the baseline and no volley zone on each half of the court; however, serves are required to be made from behind the baseline. Spendiarian & Willis Acoustics & Noise Control LLC 61 of 77 • Right Service Court c e n t a I n e Lefl Service Court Egon Volley Zone Non Volley Zane 7 Left Service, Court C e n t a l i e Right service Court I H Baseline i 10 ft -4i- 1 20ft 3fi fi 2 Figure 8.3. Pickleball Court Dimensions Sound radiated from pickleball courts will not follow the inverse square law until the distance to the point of observation is large compared to the dimensions of the court or group of courts. The inverse square law states that sound radiated from a point source will decrease in level at a rate of 6 dB for every doubling in distance. As seen in Figure 8.4, this does not hold true for distributions of sound sources at close range. The figure compares two sound sources at the opposite baselines of a pickleball court to a single source approximation located at the center of the court. The vertical dashed green lines represent the edges of the concrete pad. The lower graph is the difference between the two curves in the graph above. The point of observation must be almost three court lengths before the level difference is within 0.5 dB. Spendiarian & Willis Acoustics & Noise Control LLC 62 of 77 85 80 75 au 70 oi 65 'v 60 0 r 55 50 4.0 3.5 in 3.0 2.5 cL 2.0 — Singie source — 2 sources J 0.5 0.0 —200 —150 • —100 —50 0 50 Distance (ft) 100 150 200 Figure 8.4. Sound Pressure Level at Distance from Court Center for One and Two Sources For this reason, it is recommended to use multiple sound sources on each pickleball court when constructing an acoustical model of the courts. A vertical area source, i.e. a distribution of sound sources on a vertical plane located at the baseline at each end of each court extending the width of the baseline and from the playing surface to a height of 8 feet, is recommended. This arrangement is chosen for simplicity and to better ensure that the extents of noise barriers are not underestimated in the noise abatement planning stage. 8.5.2 Pickleball Court Directivity As described in Section 6.4, pickleball courts have a directivity pattern that is bidirectional. Measurements at numerous pickleball courts have shown that the directivity pattern can be Spendiarian & Willis Acoustics & Noise Control LLC 63 of 77 approximated as shown in Table 8.1 or by using Eq. 8.1 where 0 is the angle of the receiver with respect to the direction of play and D is the attenuation in decibels from the directivity. D=201ogio(J(cos2(8)+10(-55hb0)sin2(8))) Angle Attenuation (deg) (dB) 0 0.0 10 -0.1 20 -0.4 30 -0.8 40 -1.4 50 -2.2 60 -3.1 70 -4.0 80 -4.7 90 -5.0 100 -4.7 110 -4.0 120 -3.1 130 -2.2 140 -1.4 150 -0.8 160 -0.4 170 -0.1 180 0.0 Table 8.1. Pickleball Court Directivity Pattern Spendiarian & Willis Acoustics & Noise Control LLC 64 of 77 (8.1) 9. Noise Abatement Methods When a noise impact assessment indicates that activities planned for a site exceed the limits set in the noise regulations, a noise abatement plan to bring the site into compliance should be prepared by a qualified acoustical engineer. 9.1 Setbacks A noise abatement plan begins with sufficient setback to noise sensitive areas to make abatement treatments effective. Any given noise abatement treatment will produce a limited amount insert loss or attenuation. A noise abatement plan for a site generally consists of a number of different treatments that work together to achieve an acceptable sound level in the surrounding area. Any deficit in the amount noise reduction achievable through mitigation treatments must be made up for in setback. In short, the setback is what makes the rest of the noise abatement plan possible. One approach to setbacks is to simply prescribe a minimum setback with regard to all residential land uses. This has been done recently by Park City, Utah. Under their new pickleball code amendment [Park City], proposed pickleball courts within 600 feet of residential properties must have a noise abatement plan prepared. Pickleball courts within 150 feet of residential properties are not permitted. This approach has the advantage of being easy to understand and apply; however, there are some situations where it may not be possible to create an effective noise abatement plan at 150 feet due to elevation differences or multi -story housing that make sufficient shielding by a sound wall impractical or impossible. In some special cases it may be possible to mitigate pickleball courts closer than 150 feet. Thus a 150 foot setback requirement would be overly restrictive in these applications. Pickleball courts within 100 feet of residential land uses have proven to be problematic resulting in lawsuits, strict limitations on usage, and court closures. Courts within 150 feet of residential land uses require careful noise abatement planning using modern methods of noise assessment for highly impulsive sound such as ANSI S12.9 Part 4 described in previous chapters and strict adherence to design specifications. 9.2 Noise Barriers 9.2.1 Performance Requirements Sound walls and fence covers are the main noise abatement treatments utilized for pickleball noise control. Sound walls are a more permanent and aesthetic solution while fence covers have lower material and installation costs. Both types of barriers can have reflective or sound absorbing surfaces. Spendiarian & Willis Acoustics & Noise Control LLC 65 of 77 There are a variety of materials and products available that are acceptable for pickleball mitigation. It is important that they meet a few minimum requirements. Sound must not be able to penetrate though the barrier material. For pickleball, this means the barrier material must have a minimum sound transmission class (STC) of 20. This is not difficult to achieve with many solid materials that can include many options from mass -loaded vinyl (MLV) fence covers to masonry walls. Materials such as wind screens attached to court fencing and vegetation in the form of a hedges provide a level of visual privacy, but should not be considered noise abatement treatments. In order to maintain the integrity of the barrier transmission loss, penetrations in the barrier surfaces cannot exceed 1% of the surface area. There can be no gaps between the bottom of the barrier and the ground or between barrier sections. Fence covers must be installed with the manufacturer's recommended amount of panel overlap. 9.2.2 Fence Cover Safety Notice IMPORTANT Standard chain link court fencing may not be rated for wind loading with a solid material attached. This can pose a danger of fence collapse in high winds. Many fence manufacturers produce reinforcement kits to stabilize fencing for this type of loading. It is important to consult with the fence manufacturer or a structural engineer prior to attaching MLV, sound blankets, or anything other solid material to an existing open link fence. 9.2.3 Parallel Surfaces A common problem encountered when designing a noise barrier system for pickleball courts is the need to shield homes on opposite sides of the courts. Arranging reflective noise barriers so that they have parallel faces creates a situation where the sound is trapped between the interior surfaces and cannot dissipate. It has nowhere to go but over the noise barrier. This will significantly degrade its acoustical performance. If this layout cannot be avoided by changing the relative positions of the two walls, sound absorption will be needed on the interior surfaces to control acoustical energy buildup. Figure 9.1 shows a performance comparison of several surface materials on opposite sides of two pickleball courts arranged end to end. Carsonite is a sound wall system with integrated sound absorption. It is commonly used for noise mitigation along roadways and absorbs well at 1,000 Hz, the critical frequency for pickleball paddle impacts. AudioSeal is an outdoor sound absorbing blanket material that can be attached to a fence. It does not absorb as well as the Carsonite at higher frequencies, but still performs adequately. The MLV curve is notably higher than the AudioSeal and Carsonite curves due to its high reflectivity at 1,000 Hz. Spendiarian & Willis Acoustics & Noise Control LLC 66 of 77 1 * * — Mo barrier - AudioSeal Carsonite i - MLV - 40 30 r LI_I - 20 - 10 –400 -340 –2413 –1 qq 0//yy �y '0 Position (ft) 200 Figure 9.1. Performance Comparison of Interior Parallel Surfaces of Noise Barriers It should also be noted that the slopes of the AudioSeal and Carsonite curves are almost identical to the slope of the curve for no noise barrier. The MLV curve has a notably shallower slope that trends toward the no barrier use case at distances farther from the noise barrier. This is the result of the large number of high amplitude image sources produced by reflective interior surfaces of the MLV. Note: The ISO 9613 standard contains provisions for only one reflection. Acoustical simulation software implementing this standard will not calculate the case of parallel walls accurately. The above figure was created using multiple image sources and 40th order reflections for the MLV surfaces in order to get convergence on a solution. 9.2.4 Lowering Pickleball Courts One approach to free standing sound walls is to lower the elevation of the pickleball courts by excavating the soil at the location of the courts and using it to create a berm next to the courts. While this can have some acoustical benefits in some situations, it is more of a cost saving design choice. By constructing the sound wall on top of the berm, a lower wall height will be Spendiarian & Willis Acoustics & Noise Control LLC 67 of 77 required and the wall will be less expensive to build. 9.2.5 Ventilation and Air Flow In summer, pickleball courts, like any outdoor sport played on a hard court, can become hot. Sound walls and fence covers will impede the air flow over the courts and make the courts feel even warmer. It may be possible to alleviate this to a degree by using overlapping wall sections that allow some breeze to pass through. This usually requires an overlap of at least four times the width of the gap between the wall sections. Sound absorbing material may also be needed in the gap to control flutter reflections that allow sound from the pickleball courts to work its way through the overlap. There must be no line of sight to players on the courts possible through the gap. If necessary, add a wall extension to shield the outside opening of the overlap. This wall layout can also be used as a passageway for ingress and egress. 1 9.3 Court Orientation Exterior Figure 9.2. Sound Wall Overlap Pickleball Court From the examples of pickleball court directivity in Section 7.1, it is apparent that the orientation of pickleball courts can be used as a noise mitigation measure. By turning the courts so that a noise sensitive area is to the side of the courts, sound levels in that direction can be reduced 3 to 5 dBA. This may not be an ideal solution in some situations. It is preferable to have the direction of play roughly north -south to reduce glare from the sun during play. It is, however, worth the effort to take advantage of this characteristic of pickleball paddle radiation when it will not interfere with the use of the courts. 9.4 Sound Masking 9.4.1 Masking Requirements Masking of a sound source refers to changing the threshold of hearing by introducing another Spendiarian & Willis Acoustics & Noise Control LLC 68 of 77 sound source such that the first sound source can no longer be heard. This is difficult to achieve with impulsive sounds because of their high peak sound pressure levels. Since impulsive sound is by nature intermittent and of limited duration, a masking source would have to operate continuously at a high amplitude in order to mask the impulse. This will often create a new noise issue. Pickleball paddle impacts produce sound mostly in the 1,000 Hz octave band. The masking source must therefore also product sufficient sound in the 1,000 Hz octave band to cover the sound of the paddle impacts. 9.4.2 Roadways Roadways are a broadband, continuous sound source. In general, even busy highways are not able to mask pickleball courts due to the high peak sound pressures of the paddle impacts. Traffic noise tends to be mostly low to mid frequency sound and does not have sufficient energy in the 1,000 Hz octave band to effectively mask pickleball. It appears to be a common perception that placing pickleball courts in neighborhoods located close to main arteries or interstates will prevent noise issues due to the sound from the roadway. In practice, this has not proven to be the case as seen at Glenhaven Park in La Canada Flintridge, California [La Canada Flintridge]. This neighborhood park is located adjacent to Interstate 210 on the north side of Los Angeles. 9.4.3 Fountains There is some evidence that water fountains can be beneficial under certain conditions. As discussed above, a masking source must produce sufficient sound in the 1,000 Hz octave band and operate at all times in order to mask pickleball. Water falling on water can produce significant sound in the 1,000 Hz octave band. Fountains located close to a noise sensitive area such as a back patio that is several hundred feet from pickleball courts may produce partial masking of paddle impacts from the courts. It may be possible to reduce this distance with a sound wall system at the pickleball courts. For noise sensitive areas close to pickleball courts this is not likely to be an effective noise abatement treatment. Larger noise sensitive areas or larger numbers of homes will require multiple fountains in order to keep the distance from the fountains to the individual homes relatively small compared to the distance to the pickleball courts. 9.5 Full Enclosure of Pickleball Courts For outdoor pickleball courts that cannot be mitigated because of insufficient available setback, topography, elevation features of the surrounding structures, or some other reason, the only remaining noise abatement option may be a full enclosure to contain the sound. Any penetrations in the building shell will need to be analyzed for sound leakage including doors, windows, ventilation, exhaust fans, etc. Vestibule doors may be necessary in some applications where ingress and egress face noise sensitive areas. Spendiarian & Willis Acoustics & Noise Control LLC 69 of 77 Indoor courts with bay doors opening away from noise sensitive areas can also work in some instances. In this use case, a room analysis of the reverberant field will need to be done and the amount of sound power exiting through the bay doors calculated from the direct and reverberant sound fields. Buildings can be much higher than free standing wall and provide a better performing noise barrier. 9.6 Noise Control Policy 9.6.1 Hours of Operation Limiting the hours of operation of the pickleball courts to certain times of the day or days of the week can sometimes be an effective noise control strategy. These arrangements are often negotiated with neighbors. 9.6.2 Restrict Players Allowed to Use Courts In some cases, restricting court usage to, for example, club members and their accompanied guests can increase accountability for how the courts are used. While this may also reduce the amount of players that use the courts, noise abatement planning should assume the courts will be used at full capacity. 9.6.3 Speech A pickleball court properly mitigated for paddle impacts will generally not have noise issues related to the loudness of speech on the courts. Noise issues with speech are for the most part related to content rather than sound level. If this is the case, a prohibit on swearing and other offensive speech may be necessary. 9.6.4 Restrictions on Equipment Quieter Equipment In practice, the enforcement of the use of specific types of pickleball equipment, paddles and balls, has proven to be difficult to manage for home owners associations, country clubs, parks, and most other types of pickleball facility. In order for this to be considered a noise abatement measure, there must be a clear policy in place and personnel dedicated to monitoring activity on the courts to ensure unsanctioned equipment is not in use. Paddles There has been an effort in the pickleball paddle industry to move to quieter designs and most players are already using this "green list" equipment as it is referred to. Measurements by Spendiarian & Willis at a number of pickleball facilities have found that the mean sound exposure level of paddle impacts, when normalized to distance and ground type, is very consistent. This indicates that, in aggregate, most players are either using essentially the same equipment or that there is not a significant acoustical difference in the equipment used. During Spendiarian & Willis Acoustics & Noise Control LLC 70 of 77 testing where the make and model of the paddles in use have been recorded, it has been found that most players were using green list paddles. At the present time green list paddles should not be considered a noise control measure since most players are already using this equipment anyway. Foam Balls Measurements by Spendiarian & Willis comparing foam pickleballs to common regulation balls has shown that the foam balls can be 8 to 9 dB quieter than regulation balls. While the use of foam balls is an effective noise abatement measure, it is undesirable for pickleball players as the foam balls play very differently from the regulation balls and cannot be used in tournaments or to train for them. Spendiarian & Willis Acoustics & Noise Control LLC 71 of 77 10. Site Planning Considerations for Pickleball 10.1 When a Noise Impact Assessment Is Needed Courts located within 350 feet of residential properties in most cases require noise abatement. Pickleball court sites within 500 to 600 feet of noise sensitive areas should be reviewed by a qualified acoustical engineer in the site selection phase of the project. In the case that the ground between the pickleball courts and receiving property is water this distance may extend 800 to 1,000 feet in some cases. Courts located within 150 feet of homes require careful and often extensive noise abatement design to avoid complaints. Placing open air pickleball courts within 100 feet of residential properties is not recommended. 10.2 Site Selection 10.2.1 Available Setbacks The most important factor to consider in selecting a site for pickleball courts is the distance to adjacent residential land uses. While a noise barrier such as a sound wall or mass -loaded vinyl fence cover can be effective in reducing noise impact, it can only provide a limited amount of insertion loss, usually between 8 and 12 dB depending on the ground it is installed on, flanking paths, reflecting surfaces, and other factors. The rest of the noise reduction required to meet acceptable sound levels must mostly be gained through distance. It is important to ensure that there is enough buffer so that noise abatement installed can be adequately effective. Other site conditions that may increase the setback required are discussed in the following subsections. 10.2.2 Proximity to Multi -story Residential Structures In order for a noise barrier to be effective it must be able to block the line of sight from the sound source to the receiving land use. Pickleball paddle impacts can occur from near the elevation of the playing surface to a height of about 8 feet above it. Multi -story housing located close to the proposed pickleball courts may not be adequately shielded a wall system. This can affect upper level windows, balconies, raised decks, other amenities located above ground level. These need to be included in the noise impact assessment of the proposed pickleball courts. 10.2.3 Topography Similar to housing with floors above ground level, homes sitting at an elevation higher than the proposed pickleball courts can also be difficult to shield with a noise barrier. In addition, refraction caused by temperature gradients over certain ground can effectively cause sound to travel farther. Refraction is the bending of the path sound travels towards regions of Spendiarian & Willis Acoustics & Noise Control LLC 72 of 77 lower sound speed, e.g cooler air. This can be the result of temperature stratification of the atmosphere or wind. In low lying places where cool air tends to collect in the evenings or over irrigated ground where evaporative cooling can occur such as a golf course, a temperature lapse condition can develop with warm air above and cool air below. This will result in sound arcing down toward the ground. Refraction caused by a temperature lapse condition can result in sound arcing over obstacles on the ground that would normally impede its propagation thereby making it louder at farther distances. Parks located at the bottom of a valley can pose a particular challenge as they tend to experience these conditions regularly. Further, the sides of the valley may trap sound and send it echoing back to locations on the opposite side. Valleys often require a detailed propagation study to understand how sound moves through the area at different times of the day. 10.3 Tournaments The main difference in sound from pickleball courts during tournaments will be spectators. The noise assessment and abatement planning should include a speech analysis based on the number and location of spectators. This has been described in Section 8.4. If a PA system is to be used for announcements, limits on the system gain should be established to ensure sound levels reaching the surrounding properties remain acceptable. Noise monitoring may also be employed at the property boundaries. This involves placing one or more microphones near noise sensitive areas so that the sound system operator can monitor sound levels in real time and make any necessary adjustments. Spendiarian & Willis Acoustics & Noise Control LLC 73 of 77 11. Conclusions 11.1 Best Practices in Noise Assessment and Regulation Basic methodologies and best practices for community noise assessment, environmental acoustics measurements, and noise regulation documents have been discussed. The group of ANSI standards in S12.9 represents the current best practices in community noise assessment. The measurement methodology and sound classifications in Part 4 of the standard (harmonized with International Organization for Standardization standard ISO 1996) have been implemented under European Union Directive 2002/49 and in a number of Asian countries. ANSI S12.9 Parts 4 and 5 have been used as the basis for the recommendations in this document. 11.2 Characteristics of Pickleball Sound The most notable sounds from pickleball courts are the popping sound produced when a pickleball contacts a paddle and speech. It is the popping sound of the paddle impacts that produces the greatest number of noise complaints. This sound has been classified as highly impulsive for the purpose of noise assessment under ANSI S12.9 Part 4. 11.3 Noise Impact Assessment of Pickleball It has been shown that averaging techniques such as equivalent -continuous and maximum fast exponential time weighted sound pressure levels (LAeq and LAmax) are not well suited for assessment of short duration impulsive sound like that produced by the impact of a pickleball on a paddle. These metrics can be expected to substantially underestimate the community response to this type of sound. Measurement procedures based on the adjusted sound exposure level according to ANSI S12.9 Part 4 have been described as a more accurate methodology for noise impact assessment of pickleball. 11.4 Noise Abatement Planning Setbacks are an important first step in mitigating pickleball courts. A noise abatement plan usually consists of a number of treatments that each contribute a certain amount of noise reduction. Any difference between the total noise reduction of the abatement treatments and that required to meet target sound levels must be made for with setbacks. Topography and multistory structures near the courts will also influence the amount of setback required. In order for a noise barrier to be effective it must block the line of sight from the sound source to the point of observation. Upper level bedroom windows and decks that are able to overlook the noise barrier will not be shielded and will likely experience a greater noise impact than at ground level. Spendiarian & Willis Acoustics & Noise Control LLC 74 of 77 Testing at numerous pickleball courts has found that the sound radiated from the paddles is directional. More sound goes in the direction of play than to the sides of the court. This characteristic can be used as a noise abatement measure by orienting pickleball courts so that the direction of play is not directed toward noise sensitive areas. Sound masking in the form of water fountains has been found to be somewhat helpful in certain situations. This is mainly where the masking sound source is much closer to the noise sensitive area than the pickleball courts and the noise sensitive area is not too close to the pickleball courts. Roadways have not been found to be effective masking sources for pickleball. In most cases, the noise abatement installed for the paddle impacts will be sufficient for speech from the courts as well. Noise complaints about speech on pickleball courts are most often related to content rather than sound level. This is best addressed through policy. 11.5 Site Planning Site review and feasibility analysis for pickleball begins by looking at available setbacks and sight lines. This will determine what noise abatement treatments may be needed and whether they can be effective on a particular site. Topography and the presence of nearby multistory housing are also important considerations that may affect required setbacks. The noise impact assessment of impulsive sound is a complex task that should be done using modern standards and best practices by an acoustical engineer with experience in psychological acoustics and signal analysis. Spendiarian & Willis Acoustics & Noise Control LLC 75 of 77 References ANSI S1.4-1983, Specification for Sound Level Meters, American National Standards Institute, 1983. ANSI S1.4-2014, Electroacoustics — Sound Level Meters — Part 1: Specifications, American National Standards Institute, 2014. ANSI S1.11-2004, Specification For Octave -Band and Fractional -Octave -Band Analog and Digital Filters, American National Standards Institute, 2004. ANSI S1.13-2005, Measurement of Sound Pressure Levels in Air, American National Standards Institute, 2005. ANSI S1.42-2001, Design Response Of Weighting Networks For Acoustical Measurements, American National Standards Institute, 2001. ANSI S1.43-1997, Specifications For Integrating -Averaging Sound Level Meters, American National Standards Institute, 1997. ANSI S3.5-1997, Methods of Calculation of the Speech Intelligibility Index, American National Standards Institute, 1997. ANSI S12.9-2013, Quantities and Procedures for Description and Measurement of Environmental Sound — Part 3: Short-term Measurements with an Observer Present, American National Standards Institute, 2013. ANSI S12.9-2021, Quantities and Procedures for Description and Measurement of Environmental Sound — Part 4: Noise Assessment and Prediction of Long Term Community Response, American National Standards Institute, 2021. ANSI S12.9-2007, Quantities and Procedures for Description and Measurement of Environmental Sound — Part 5: Sound Level Descriptors for Determination of Compatible Land Use, American National Standards Institute, 2007. ANSI S12.62-2012, Attenuation of sound during propagation outdoors — Part 2: General method of calculation, Nationally Adopted International Standards, Acoustical Society of America (ASA), 2012. Buchta, Edmund, "A field survey on annoyance caused by sounds from small firearms," Journal of the Acoustical Society of America, vol. 88 (3), September 1990. p. 1459. City of La Canada Flintridge, "Pickleball Program at Glenhaven Park to End October 28," <https://cityoflc£org/pickleball-program-at-glenhaven-park-to-end-october-28/>, October 27th, 2022. Dittrich, Kerstin and Oberfeld, Daniel, "A comparison of the temporal weighting of annoyance Spendiarian & Willis Acoustics & Noise Control LLC 76 of 77 and loudness," Journal of the Acoustical Society of America, vol. 126 (6), December 2009. p. 3168. Harris, Cyril M. (Ed.), Handbook of Acoustical Measurements and Noise Control, 3'd Edition, Acoustical Society of America, 1998. ISO 226-2003, Acoustics - Normal equal -loudness -level contours, International Organization for Standardization (ISO), 2003. ISO 1996-1, Acoustics - Description, measurement and assessment of environmental noise - Part 1: Basic quantities and assessment procedures, International Organization for Standardization (ISO), 2016. ISO 9613 Part 2, Acoustics - Attenuation of Sound During Propagation Outdoors - Part 2: General Method of Calculation, International Organization for Standardization (ISO), 1996. Park Cty, Utah, Municipal Code 15-4-22 Outdoor Pickleball Courts In Residential Areas. Adopted April, 2022. Schultz, T. J., "Synthesis of Social Surveys on Noise Annoyance," Journal of the Acoustical Society of America v. 64, pp. 377-405, 1978. Smoorenburg, G. F., Vos, J., "Rating of impulse noise, in particular shooting noise, with regard to annoyance," Journal of the Acoustical Society of America, suppl 1, vol. 73, Spring 1983. p. S48. Vos, Joos, "On the annoyance caused by impulse sounds produced by small, medium -large, and large firearms," Journal of the Acoustical Society of America, vol. 109 (1), January 2001. p. 244- 253. Vos, Joos and Houben, Mark M. J., "Enhanced awakening probability of repetitive impulse sounds," Journal of the Acoustical Society of America, vol. 134 (3), September 2013. p. 2011. Vos, Joos and Smoorenburg, Guido F., "Penalty for impulse noise, derived from annoyance for impulse and road -traffic sounds," Journal of the Acoustical Society of America, vol. 77 (1), January 1985. p. 193. World Health Organization (WHO), Night Noise Guidelines for Europe, http://www.euro.who.int, 2009. Zwicker, E. and Fastl, H., Psychoacoustics Facts and Models, 2' Edition, Springer, 1999. Spendiarian & Willis Acoustics & Noise Control LLC 77 of 77 Attachment C ANSI 512.9-2005/Part 4 (Revision of ANSI S12.9-1996/Part 4) AMERICAN NATIONAL STANDARD Quantities and Procedures for Description and Measurement of Environmental Sound — Part 4: Noise Assessment and Prediction of Long-term Community Response ANSI 512.9-2005/Part 4 Accredited Standards Committee S12, Noise Standards Secretariat Acoustical Society of America 35 Pinelawn Road, Suite 114E Melville, New York 11747-3177 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl The American National Standards Institute, Inc. (ANSI) is the national coordinator of voluntary standards development and the clearinghouse in the U.S.A. for information on national and international standards. The Acoustical Society of America (ASA) is an organization of scientists and engineers formed in 1929 to increase and diffuse the knowledge of acoustics and to promote its practical applications. 1 iranenrl In arlauinka mfnn AAICI nrrlar Y 1d911151 flnuinlnarlarl 11M/91)11 740 PIA Cinnla Ticar Iiranea nnlu Cnnuinn and natuinrkinn nrnhihitarl ANSI S12.9-2005/Part 4 (Revision of ANSI S12.9-1996/Part 4) AMERICAN NATIONAL STANDARD QUANTITIES AND PROCEDURES FOR DESCRIPTION AND MEASUREMENT OF ENVIRONMENTAL SOUND - PART 4: NOISE ASSESSMENT AND PREDICTION OF LONG-TERM COMMUNITY RESPONSE Secretariat: Acoustical Society of America Approved by: American National Standards Institute, Inc. Abstract This Standard specifies methods to assess environmental sounds and to predict the annoyance response of communities to long-term noise from any and all types of environmental sounds produced by one or more distinct or distributed sound sources. The sound sources may be separate or in various combinations. Application of the method of the Standard is limited to areas where people reside and related long-term land uses. This Standard does not address the effects of intrusive sound on people in areas of short-term use such as parks and wilderness areas, nor does it address other effects of noise such as sleep disturbance or health effects. This Standard does not provide a method to predict the community response to short-term, infrequent, non -repetitive sources of sound. © Acoustical Society of America 2005 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl AMERICAN NATIONAL STANDARDS ON ACOUSTICS The Acoustical Society of America (ASA) provides the Secretariat for Accredited Standards Committees S1 on Acoustics, S2 on Mechanical Vibration and Shock, S3 on Bioacoustics, and S12 on Noise. These committees have wide representation from the technical community (manufacturers, consumers, trade associations, organizations with a general interest, and government representatives). The standards are published by the Acoustical Society of America as American National Standards after approval by their respective Standards Committees and the American National Standards Institute. These standards are developed and published as a public service to provide standards useful to the public, industry, and consumers, and to Federal, State, and local governments. Each of the accredited Standards Committees [operating in accordance with procedures approved by American National Standards Institute (ANSI)] is responsible for developing, voting upon, and maintaining or revising its own Standards. The ASA Standards Secretariat administers Committee organization and activity and provides liaison between the Accredited Standards Committees and ANSI. After the Standards have been produced and adopted by the Accredited Standards Committees, and approved as American National Standards by ANSI, the ASA Standards Secretariat arranges for their publication and distribution. An American National Standard implies a consensus of those substantially concerned with its scope and provisions. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered and that a concerted effort be made towards their resolution. The use of an American National Standard is completely voluntary. Their existence does not in any respect preclude anyone, whether he or she has approved the Standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the Standards. NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this Standard. Acoustical Society of America ASA Secretariat 35 Pinelawn Road, Suite 114E Melville, New York 11747-3177 Telephone: 1 (631) 390-0215 Fax: 1 (631) 390-0217 E-mail: asastds@aip.org © 2005 by Acoustical Society of America. This standard may not be reproduced in whole or in part in any form for sale, promotion, or any commercial purpose, or any purpose not falling within the provisions of the U.S. Copyright Act of 1976, without prior written permission of the publisher. For permission, address a request to the Standards Secretariat of the Acoustical Society of America. © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl Contents 1 Scope 1 2 Normative references 2 3 Terms and definitions 2 4 Descriptors for environmental sounds 4 4.1 Single -event sounds 4 4.2 Continuous sounds 4 4.3 Repetitive single -event sounds 5 5 Sound measurement locations 5 6 Adjustments for background sound 5 6.1 General 5 6.2 Specific requirements 5 7 Method to assess environmental sounds either singly or in combination 6 7.1 General environmental sounds 6 7.2 Adjustments to general environmental sound 8 8 Reporting assessments of environmental sounds and prediction of long-term community annoyance response 12 8.1 Use of A -weighted sound exposure and day -night average sound level 12 8.2 Assessment of environmental sounds 12 8.3 Prediction of long-term annoyance response of communities 12 8.4 Reporting 12 Annex A Adjustments for background sound 14 A.1 Introduction 14 A.2 Mathematical development 15 A.3 Background sound adjustment situations 16 Annex B High-energy impulsive sounds 18 B.1 Introduction 18 B.2 Fundamental descriptor 18 B.3 Measurement 18 B.4 Calculation of adjusted sound exposure level for high-energy impulsive sounds from C - weighted sound exposure level 18 B.5 Calculation of adjusted sound exposure level from C -weighted sound exposure level 18 B.6 Calculation of adjusted sound exposure level from C -weighted sound exposure 19 B.7 Use of adjusted sound exposure 19 Annex C Sounds with tonal content 20 Annex D Sounds with strong low -frequency content 21 D.1 Introduction 21 D.2 Analysis factors 21 D.3 Applicability 21 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl D.4 Descriptor 22 D.5 Adjusted sound exposures for sounds with strong low -frequency content 22 D.6 Use of adjusted sound exposure 23 D.7 Noise -induced rattles 23 Annex E Onset rate for airplane flybys 24 Annex F Estimated percentage of a population highly annoyed as a function of adjusted day -night sound level 25 F.1 Introduction 25 F.2 The Dose -response function 25 F.3 Qualifications to the dose -response function 26 Annex G Assessing the complaint potential of high -amplitude impulse noise 29 G.1 Introduction 29 G.2 Complaint criteria 29 G.3 Complaint risk prediction 29 Annex H Loudness -level weighting 31 H.1 Introduction 31 H.2 The method 31 Bibliography 35 Figures Figure F.1 — Percentage of respondents highly annoyed by road traffic sounds, as a function of the A - weighted day -night level 26 Figure H.1 — Equal loudness level contours in phons from ISO 226-1987. The non -shaded area shows the frequency range where, approximately, a 10 -dB change in sound pressure level corresponds to a 10 -dB change in phon level. At low frequencies this relationship does not occur. For example, at 31 Hz, a 10 -dB change in sound pressure level corresponds to about a 20 -dB change in phon level. 33 Figure H.2 — Generalized house TL for windows open on the order of 5 cm. 33 Tables Table 1 — Relation between sound exposure level and sound exposure for a constant sound level of 60 dB. 8 Table 2 — Adjustment factors and level adjustments for assessment of all types of environmental sounds. 11 Table F.1 — Annual -average adjusted A -weighted day -night sound levels and corresponding total adjusted day -night sound exposures and percentages of a population highly annoyed 28 Table G.1 – Complaint Risk Criteria 30 Table H.1 — Coefficients for calculation loudness level from band sound pressure level. The table also includes the house filter characteristics shown in Figure H.2. 34 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl Foreword [This Foreword is for information only, and is not a part of the American National Standard ANSI S12.9 - 2005/Part 4 American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound - Part 4: Noise Assessment and Prediction of Long -Term Community Response.] This standard comprises a part of a group of definitions, standards, and specifications for use in noise. It was developed and approved by Accredited Standards Committee S12 Noise, under its approved operating procedures. Those procedures have been accredited by the American National Standards Institute (ANSI). The Scope of Accredited Standards Committee S12 is as follows: Standards, specifications, and terminology in the field of acoustical noise pertaining to methods of measurement, evaluation, and control; including biological safety, tolerance, and comfort, and physical acoustics as related to environmental and occupational noise. This standard is a revision of ANSI S12.9-1996/Part 4, which has been technically revised. The changes in this edition harmonize with the new material added to ISO 1996-1:2003. This includes a minor change to high-energy impulse noise assessment (less than 1 dB) so that it is totally in sync with ISO. Second, as appropriate, ISO assessment adjustments have been included. Also, some new cautionary notes from ISO are added to the estimation of "highly annoyed" as notes to the informative annex. A new Annex G addresses complaints in the limited situation of high-energy impulsive noise. The current edition of ISO 1996-1:2003 actually began as the text of ANSI S12.9 - 1996/Part 4. However, the ISO standard was substantially revised during the WG and committee deliberations. For example, ISO recognizes the more general Day -Evening -Night Sound Level in contrast to S12's Day - Night Sound Level. Nighttime hours are not given in ISO because they vary from country to country. The terms "background" sound and "ambient" sound are NOT used in ISO because they have diametrically opposed meanings in different countries and regions. There are many other differences of this nature. ISO uses "rating" sound level; ANSI uses "adjusted" sound level, etc. At the time this Standard was submitted to Accredited Standards Committee S12, Noise for approval, the membership was as follows: R.D. Hellweg, Chair R.D. Godfrey, Vice -Chair S.B. Blaeser, Secretary Acoustical Society of America B.M. Brooks P.D. Schomer (Alt.) Aearo Company E.H. Berger Air -Conditioning and Refrigeration Institute R. Seel D. Brown (Alt.) Alcoa Inc. W.D. Gallagher ©Acoustical Society of America 2005 — All rights reserved III 1 iranenrl In arlauin4a mfnn AAICI nrrlar Y 1d91f151 flnuinInarlarl 11M/9f111 740 PIA Cinnla near Iiranea nnls, Cnnuinn and natuinrkinn nrnhihitarl American Industrial Hygiene Association D. Driscoll J. Banach (Alt.) American Speech -Hearing -Language Association L.A. Wilber V. Gladstone (Alt.) American Society of Heating, Refrigeration, and Air -Conditioning R.J. Peppin E. Rosenberg (Alt.) Bruel & Kjaer Instruments, Inc. M. Alexander J. Chou (Alt.) Caterpillar, Inc. K.G. Meitl D.G. Roley (Alt.) Compressed Air and Gas Institute J.H. Addington D.R. Bookshar (Alt.) Council for Accreditation in Occupational Hearing Conservation J. Banach E.H. Berger (Alt.) Emerson Electric — Copeland Corporation A.T. Herfat General Motors D. Moore Howard Leight Industries V. Larson E. Woo (Alt.) International Safety Equipment Association J. Birkner J.C. Bradley (Alt.) Information Technology Industry Council R.D. Hellweg J. Rosenberg (Alt.) Institute of Noise Control Engineering B. Tinianov M. Lucas (Alt.) James, Anderson & Associates R.R. Anderson R.R. James (Alt.) John Deere K. Cone Larson Davis Laboratories L. Davis K. Cox (Alt.) National Council of Acoustical Consultants J. Erdreich G.E. Winzer (Alt.) National Hearing Conservation Association K. Michael National Institute for Occupational Safety and Health W.J. Murphy Noise Control Engineering, Inc. M. Bahtiarian R. Fischer (Alt.) Noise Pollution Clearinghouse L. Blomberg North American Insulation Manufacturers Association R.D. Godfrey Plantronics, Inc. A.K. Woo iv © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In arlauin4a mfnn AAICI nrrlar Y 1d91f151 flnuinlnarlarl 11M/9f111 7•AQ PFA Cinnla near Iiranea nnlu Cnnuinn and natuinrkinn nrnhihitarl Power Tool Institute, Inc. W.D. Spencer M. Hickok (Alt.) Quest Technologies, Inc. M. Wurm P. Battenberg (Alt.) Rubber Manufacturers Association S. Butcher A. Hartke (Alt.) SAE C. Michaels U.S. Air Force (USAF) R. McKinley U.S. Army Aeromedical Research Lab W. Ahroon N. Alem (Alt.) U.S. Army Center for Health Promotion and Preventive Medicine W.A. Russell W. Whiteford (Alt.) U.S. Army Construction Engineering Research Laboratories M. White L. Pater (Alt.) U.S. Department of Transportation A. Konheim U.S. Army Human Research and Engineering Directorate T.R. Letowski L. Babeu (Alt.) U.S. Naval Surface Warfare Center Carderock M. Craun J. Niemiec (Alt.) Individual Experts of Accredited Standards Committee S12, Noise, were: P.K. Baade L.L. Beranek E.H. Berger S. Bly B.M. Brooks A.J. Campanella K.M. Eldred L.S. Finegold W.J. Galloway R.D. Hellweg R.K. Hillquist W.W. Lang R.J. Peppin J. Pope P.D. Schomer J.P. Seiler L.C. Sutherland W.R. Thornton L. A. Wilber G. E. Winzer G.S.K. Wong Working Group S12/WG 15, Measurement and Evaluation of Outdoor Community Noise, which assisted Accredited Standards Committee S12, Noise, in the development of this standard, had the following membership. G.A. Daigle K.M. Eldred A.G. Konheim P.D. Schomer, Chair L.S. Finegold L. Pater G.A. Luz A.H. Marsh Suggestions for improvements of this standard will be welcomed. They should be sent to Accredited Standards Committee S12, Noise, in care of the Standards Secretariat of the Acoustical Society of America, 35 Pinelawn Road, Suite 114E, Melville, New York 11747-3177. Telephone: 631-390-0215; FAX: 631-390-0217; E-mail: asastds@aip.org © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d91f151 flnuinlnerlarl 11M/9f111 7•AQ PFA Cinnla near Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl Introduction 0.1 Part 1 of ANSI S12.9 defines day -night average sound level and other descriptors of community noise. Part 2 of ANSI S12.9 describes measurement procedures. ANSI S12.9/Part 5 provides a recommended relation between long-term usages of land and day -night average sound level for purposes of long-term land -use planning. Since the early 1970s, many agencies within the United States of America have used day -night average sound level as the fundamental descriptor to predict the community response to environmental sounds. 0.2 The 1978 seminal paper by T.J. Schultz demonstrated the efficacy of day -night average sound level for predicting the annoyance response of a community as a result of noise from highway traffic, railroad, aircraft, and some industrial sites. Implementation of the concept of day -night average sound level for prediction of community response often combined the sound exposures from such sources. 0.3 Day -night average sound level has been used to predict the annoyance response of communities to types of noises that were not included in the Schultz database for the relation between the percentage of a population expressing high annoyance and the corresponding day -night average sound level. These additional types of noises include sounds with special characteristics, such as impulsiveness, dominant pure tones, rapid onset, and strong low -frequency content. 0.4 Technical reports and articles published in refereed engineering and scientific journals demonstrated that the community response to these sounds may be predicted, provided suitable adjustments are applied. A practical procedure to apply these adjustments is provided by this Standard. 0.5 For situations where activity interference is the major concern, use of adjusted day -night average sound level or adjusted total day -night sound exposure may not be appropriate. For example, day -night average sound level without adjustments may be a better predictor of speech interference than adjusted day -night average sound level. Descriptors such as maximum A -weighted sound level, time -above, or speech interference level may be even more appropriate for predicting speech interference. vi © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl AMERICAN NATIONAL STANDARD ANSI 512.9-2005/Part 4 American National Standard QUANTITIES AND PROCEDURES FOR DESCRIPTION AND MEASUREMENT OF ENVIRONMENTAL SOUND - PART 4: NOISE ASSESSMENT AND PREDICTION OF LONG-TERM COMMUNITY RESPONSE 1 Scope 1.1 This Standard specifies methods to assess environmental sounds and to predict the potential annoyance response of a community to outdoor long-term noise from any and all types of environmental sounds from one or more discrete or distributed sound sources. The sound sources may be separate or in various combinations. Application of the prediction method is limited to areas where people reside and to related long-term land uses. NOTE The long-term period is typically one year. However, the user of this Standard can employ these methods for shorter periods of time, but they should report this change and not attempt to predict percent highly annoyed using Clause 8.3 or Annex F, since the Annex F data all represent long-term situations. 1.2 This Standard describes adjustments for sounds that have special characteristics so that the long-term community response to such sounds can be predicted by a method that is based on day - night average sound level or total day -night sound exposure. Sounds, such as from highway traffic, are evaluated directly by sound exposure or sound level without adjustment. The prediction method is directly analogous to the use of day -night average sound level to predict the response of a community to general environmental sounds. 1.3 This Standard does not address the effects of short-term exposure of people to intrusive sounds in locations such as parks and wilderness areas. The Standard also does not address other effects of noise such as sleep disturbance or health effects. This Standard does not provide a method to predict the response of a community to short-term, infrequent, non -repetitive sources of sound. 1.4 This Standard introduces the application of new descriptors: adjusted sound exposure and adjusted sound exposure level. The new descriptors are closely related to sound exposure and sound exposure level, respectively. The new descriptors are introduced to facilitate the prediction of the response of communities to the wide range of outdoor sounds covered by the scope of the Standard. 1.5 The sounds are assessed either singly or in combination, allowing for consideration, when necessary, of the special characteristics of impulsiveness, tonality, onset rate, and low -frequency content. In the same manner as sound exposure and sound exposure level are used to generate total day -night sound exposure or total day -night average sound level, adjusted sound exposure or adjusted sound exposure level are used to generate adjusted total day -night sound exposure or adjusted day -night average sound level. 1.6 Annoyance is not the only possible measure of community response. One frequently cited measure is numbers of complaints, sometimes normalized to numbers of inhabitants. Complaints can be particularly relevant near factories and plants, by airports and military installations, etc. Complaints do not correlate well with long-term average metrics such as DNL (see Refs. 7 and 8 for © Acoustical Society of America 2005 — All rights reserved 1 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnls, Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 example). Unfortunately, in general, metrics to predict the likelihood and prevalence of complaints do not yet exist with sufficient accuracy. One notable exception is the high-energy impulse sound generated by military activities and similar civilian noise sources, and informative Annex G provides procedures for assessing the risk of noise complaints from such sources. 1.7 The addition of adjustments eliminates the possibility to measure the total adjusted sound exposure or sound exposure level in a general situation that comprises a variety of sound sources (e.g., the combination of a highway leading to an airport and the airport itself). As a possible measurable alternative, this Standard introduces a new metric based on the equal -loudness level contours that were contained in ISO 226:1987. This new method uses the equal -loudness level contours as a set of dynamic filters that vary both with amplitude and frequency. This method is described in informative Annex H. 2 Normative references The following referenced documents are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. [1] ANSI S1.1-1994 (R 2004) American National Standard Acoustical Terminology. [2] ANSI S12.9-1988/Part 1 (R 2003) American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound - Part 1. [3] ANSI S12.9-1992/Part 2 (R 2003) American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound - Part 2: Measurement of Long -Term Wide - Area Sound. [4] ANSI S12.9-1993/Part 3 (R 2003) American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound - Part 3: Short-term Measurements with an Observer Present. [5] ANSI 512.9-1998/Part 5 (R 2003) American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound - Part 5: Sound Level Descriptors for Determination of Compatible Land Use. [6] ANSI S1.13-2005 American National Standard Methods for the Measurement of Sound Pressure Levels in Air. 3 Terms and definitions For the purposes of this standard, the terms and definitions given in ANSI S1.1-1994 and the following apply: 3.1(a) adjusted sound exposure. Frequency -weighted sound exposure adjusted for the change in annoyance caused by certain impulsive sounds, the presence of prominent discrete -frequency tones, sounds that startle because of their rapid onset rate, sounds with strong low -frequency content, and the presence of masking background sound. Unit, pascal -squared second (Pa2s); symbol, N. NOTE 1 Adjustments and frequency weightings for various types of sounds are given in Clause 7. NOTE 2 The unit of pascal -squared second for adjusted sound exposure has been abbreviated as "pasque." 2 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In arlauin4a mfnn AAICI nrrlar Y 1d911151 flnuinlnarlarl 11M/91)11 740 PIA Cinnla Ticar Iiranea nnlu Cnnuinn and natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 3.1(b) reference sound exposure. The product of the square of the reference sound pressure of 20 µPa and the reference time of 1 s. Unit, pascal -squared second (Pa2s); symbol, E0. 3.1(c) adjusted sound exposure level. Ten times the base -10 logarithm of the ratio of the adjusted sound exposure to the reference sound exposure E0. Unit, decibel (dB); symbol, LNE. 3.2 adjusted total day -night sound exposure. Frequency -weighted sound exposure for a 24- hour day calculated by adding adjusted sound exposure obtained during the daytime (0700-2200 hours) to ten times adjusted sound exposure obtained during the nighttime (0000-0700 and 2200-2400 hours). Unit, pascal -squared second (Pa2s); symbol, Ndn. 3.3(a) adjusted day -night average sound pressure. Square root of ratio of adjusted total day - night sound exposure to 86,400 s. Unit, pascals (Pa). 3.3(b) adjusted day -night average sound level. Ten times the base -10 logarithm of the ratio of the square of the adjusted day -night average sound pressure to the square of the reference sound pressure of 20 µPa. Unit, decibel (dB); symbol, LNdn• 3.4 impulsive sound. Sound characterized by brief excursions of sound pressure (acoustic impulses) that significantly exceed the ambient environmental sound pressure. The duration of a single impulsive sound is usually less than one second. NOTE At the time of publication, no mathematical descriptor existed to unequivocally define the presence of impulsive sound or to separate impulsive sounds into categories. 3.4.1 highly impulsive sound. Sound from one of the following enumerated categories of sound sources: small -arms gunfire, metal hammering, wood hammering, drop hammering, pile driving, drop forging, pneumatic hammering, pavement breaking, metal impacts during rail -yard shunting operation, and riveting. 3.4.2 high-energy impulsive sound. Sound from one of the following enumerated categories of sound sources: quarry and mining explosions, sonic booms, demolition and industrial processes that use high explosives, military ordnance (e.g., armor, artillery and mortar fire, and bombs), explosive ignition of rockets and missiles, explosive industrial circuit breakers, and any other explosive source where the equivalent mass of dynamite exceeds 25 g. Normally, for single impulsive sounds of concern for this Standard, the A -weighted sound exposure level will exceed 65 dB and the C -weighted sound exposure level will exceed 85 dB. 3.4.3 regular impulsive sound. Impulsive sound that is not highly impulsive sound or high-energy impulsive sound. 3.5 onset rate. Nominally, the average rate of change of sound level during the onset of a noise event. Mathematically, onset rate is the rate of change of the A -weighted event sound level between the time the event sound level first exceeds the ambient sound level by 10 dB, and the time the event sound level first exceeds a level that is 10 dB less than the event's maximum fast -time -weighted sound level. Onset rate is defined for those event sound levels for which the maximum A -frequency - weighted, fast -time -weighted sound level exceeds the ambient sound level by at least 30 dB. Unit, decibels per second (dB/s). NOTE 1 The nominal 125 -ms time constant of fast time weighting normally is not small enough to accurately determine onset rate. Onset rate should be determined from the time variation of the level of the squared sound pressure. A digital system that provides a series of short -time -average sound levels may be used. In this case, the averaging time for each sound level in the series should be no greater than 1/10 and no less than 1/25 of the time span over which the onset rate is determined. A digital or analog system with exponential time weighting also may be used. In this case, the exponential time constant should be no greater than 1/4 and no less than 1/10 of the time span over which the onset rate is determined. © Acoustical Society of America 2005 — All rights reserved 3 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 NOTE 2 A determination of onset rate should not be unduly influenced by anomalous fluctuations in the sound level. 3.6 time above. The time per stated unit time interval that the sound pressure level exceeds a criterion level (e.g., 30 s per hour). The frequency weighting or filtering (e.g., A -weighting), time weighting or integration time interval, and the unit time interval all must be stated. Typical Units: seconds (s) or minutes. 4 Descriptors for environmental sounds 4.1 Single -event sounds 4.1.1 Descriptors Sounds from single events such as the passby of a truck, the flyby of an airplane, or an explosion at a quarry are all examples of single -event sounds. Each sound can be characterized by many descriptors. These descriptors include physical quantities and the corresponding levels in decibels. The level of a descriptor and its corresponding physical quantity form a descriptor pair. Three descriptor pairs often are used to describe the sound of single events. For each of these, frequency - weighting A is understood except for high -amplitude impulsive sounds or sounds with strong low - frequency content. The preferred three descriptor pairs are: peak (frequency -weighted) sound pressure and peak (frequency -weighted) sound pressure level; maximum exponential -time -weighted sound pressure and maximum sound level; and sound exposure and sound exposure level. NOTE 1 For the above descriptor pairs, the frequency weighting should be specified if frequency -weighting A is not employed, e.g., as peak C -weighted sound pressure level, C -weighted sound exposure level. NOTE 2 For maximum sound pressure (and maximum sound level), the exponential -time -weighting should be specified, e.g., as fast (F) or slow (S). 4.1.2 Event duration Event duration shall be specified relative to some characteristic of the sound such as the time of occurrence of the maximum sound level or the time some threshold was exceeded. For example, duration may be the total time that the sound level is within 10 dB of the maximum sound level. 4.2 Continuous sounds Environmental sounds from sources such as transformers, fans, or cooling towers are examples of continuous sounds. Amplitudes of continuous sounds may be constant or slowly varying. Each sound can be characterized by many descriptors. Two descriptor pairs are commonly used to describe a continuous sound. For each of these, frequency -weighting A is commonly used. The two preferred descriptor pairs are: maximum (exponential -time -weighted) sound and maximum sound level; and time -average sound pressure and time -average (equivalent -continuous) sound level. NOTE 1 For both of the above descriptors, the frequency weighting should be specified if frequency -weighting A is not employed. 4 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d91f151 flnu.nInnrlarl 11M/9f111 740 PIA Cinnla near Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 NOTE 2 For maximum (exponential -time -weighted) sound (and maximum sound level), the exponential -time weighting should be specified, e.g., as fast (F) or slow (S). NOTE 3 See Clauses 5.1.4, 5.1.5, and 5.1.6 in ANSI 512.9-1988/Part 1 (R2003) for definitions of these quantities. 4.3 Repetitive single -event sounds Repetitive single -event environmental sounds typically are recurrences of single -event sounds. For example, during a day, the sound from traffic on a highway is the sum of the sound from multiple individual vehicle passbys. In this Standard, all repetitive single -event sounds utilize the descriptor for the particular single -event sounds and the corresponding number of events. 5 Sound measurement locations All sounds, except high-energy impulsive sounds, shall be measured or predicted as if they had been measured by a microphone outdoors, over acoustically absorptive ground (grass), at a height of approximately 1.2 m and with no nearby reflecting surfaces except the ground. Alternative microphone locations may be used, but their acoustical characteristics shall be specified. An example of an alternative location is outside an open, upper -story window in a high-rise apartment building where the purpose is to predict or assess the environmental sound at that location. High-energy impulsive sounds shall be measured or predicted as if they had been measured by a microphone within 50 mm of a hard reflecting surface (e.g., a building wall, roof, or ground plane, as appropriate). NOTE 1 A reflecting surface is required because sonic booms, which are one form of high-energy impulsive sounds, have traditionally been measured or predicted for a location on a reflecting ground plane or structure. NOTE 2 To ensure comparable data, sonic booms should be measured on a reflecting ground plane or other equivalent structure. 6 Adjustments for background sound 6.1 General Annex A discusses a general method to include adjustments for background sound. The general method is applicable to three cases: (1) the sound of concern is very noticeable and detectable in the background setting of interest, (2) the sound of concern is virtually unnoticeable and undetectable in the background setting of interest, and (3) the sound of concern is in a range such that it may be noticeable and detectable only for a portion of the time. 6.2 Specific requirements When the conditions of 6.1(2) apply and the sound is virtually unnoticeable and undetectable in the background setting of interest, then its sound exposure shall not be included in a calculation of the total sound exposure from multiple sound sources. If some particular sound is excluded, then the physical background setting shall be specified. For example, this setting may be "urban residential not near an arterial street, outdoors," or "suburban residential indoors with windows partially open," or "urban residential near an arterial street, indoors with windows closed." NOTE Direct measurements may be used to determine the background sound level prevailing for the environment. Procedures in Part 3 of ANSI S12.9 should be used to measure the background sound level. © Acoustical Society of America 2005 — All rights reserved 5 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinu.nlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Alternatively, the nominal background sound levels given in Part 3 of ANSI S12.9 may be used for various urban environments. 7 Method to assess environmental sounds either singly or in combination This Standard permits assessment of environmental sounds from individual sources or any combination of sources. If the sound has special characteristics or unusual community response, then adjusted sound exposure or adjusted sound exposure level shall be used to describe the source(s) of sound. In addition, the total adjusted sound environment shall include a weekend daytime adjustment, and is used to predict long-term community response. 7.1 General environmental sounds General environmental sounds are assessed using frequency -weighting A. (Environmental sounds with special characteristics are described in 7.2.) Sound exposure, sound exposure level, total time - period sound exposure, time -average sound level, total day -night sound exposure, and day -night average sound level are the preferred descriptors. The exposure method of presentation is described in 7.1.1, the left-hand column below. The level method of presentation is described in 7.1.2, the right- hand column below. 7.1.1 Exposure method 7.1.2 Level method 7.1.1.1 Sound exposure 7.1.2.1 Sound exposure level Sound exposure is a descriptor for characterizing Sound exposure level is a descriptor for the sound from individual acoustical events. For characterizing the sound from individual acoustical individual single -event sounds such as vehicle events. For individual single -event sounds such passbys, sound exposure may be directly as vehicle passbys, sound exposure level may be measured or predicted for the sound -producing directly measured or predicted for the sound - events under consideration. For a continuous producing events under consideration. For a source, the total time -period sound exposure may continuous source, the sound exposure level may be measured or predicted for the time period of be measured or predicted for the time period of interest. A -weighted sound exposure EA, in interest. A -weighted sound exposure level LAE, in pascal -squared seconds, may be calculated as the decibels, may be calculated as ten times the base - product of the time -mean -squared, A -weighted 10 logarithm of the ratio of the A -weighted sound sound pressure pA in pascals squared and the duration, in seconds, of the time period of interest exposure EA to the reference sound exposure Eo defined in 3.1(b), i.e., as T, i.e., as EA=pA2T. (1 a) LAE =10Ig(EA/EQ). (1b) 6 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 7.1.1.2 Total sound exposure 7.1.2.2 Time -average sound level Total sound exposure may be used to characterize Time -average sound level may be used to the sound of one or more events from individual or characterize the sound of one or more events from combined sources of sound during a time period of individual or combined sources of sound during a interest such as the hour from 1600 to 1700, time period of interest such as the hour from 1600 daytime from 0700 to 2200, or nighttime from 2200 to 1700, daytime from 0700 to 2200, or nighttime to 2400 and 0000 to 0700. Total A -weighted sound from 0000 to 0700 and 2200 to 2400. Time - exposure in a time period EA/period), in pascal- average, A -weighted sound level LA(period), in squared seconds, is the sum of the N sound decibels, is calculated from the total sound exposures EA/ from the i-th individual single -event sounds during the stated time period. exposure in the period. In mathematical notation, In mathematical notation, N EA / ' (2a) EA(period) _ / LA(period) = 10 Ig I 0.1 LAA51 (TO / T) E 10 IJ , (2b) =1 i=1 NOTE The stated time period may be of any duration where To is the reference time of 1 s and T is the such as one daytime period for one day or for any total time period in seconds for the duration of the number of days up to 365 days of a year. Furthermore, the sound exposure EA/ for the i-th event may be for any one sound source or a combination of sources. time average. NOTE For a constant time -average sound level of 60 dB, sound exposure level LAE(period) and sound exposure EA(period) are related as shown in Table 1 for selected integration time periods T. 7.1.1.3 Total day -night sound exposure 7.1.2.3 Day -night average sound level Total day -night sound exposure is a descriptor for Day -night average sound level is a descriptor for characterizing long-term acoustical environments characterizing long-term acoustical environments from sounds of one or more events from individual from sounds of one or more events from individual or combined sound sources. Total day -night sound or combined sound sources. Day -night average exposure EAdn, in pascal -squared seconds, is the sound level, in decibels, is calculated from ten sum of daytime sound exposures plus 10 times the times the base -10 logarithm of the sum of the sum of nighttime sound exposures where daytime daytime sound exposures plus the nighttime sound is the 15 hours from 0700 to 2200 and nighttime is exposures, where sound exposure levels or sound the nine hours from 0000 to 0700 and from 2200 to levels occurring during nighttime hours are 2400 in any 24-hour day. weighted by 10 dB. In mathematical notation, Nd Nn In mathematical notation, Nd 0.1LAE.1 EAdn = 1 EAi +10 1 EAi Ldn = 10 Ig (15/24 )(T0 / Td) E 10 + i= 1 i= 1 (3a) i =1 - _ (3b) = EAd + l OEAn , 10 Ig Nn 0. l(L•+ 10 (9/24 )(TO / Tn) 110 AE/ )1 where Nd is the number of daytime sound- exposures and Nn is the number of nighttime sound exposures. = 10 Ig i = 1 (15/24 )100' 1 Ld + (9/24 )100.1(Ln ] + 10)1 0)LI LI where Td = the 15 daytime hours or 54,000 s and Tn = the 9 nighttime hours or 32,400 s. © Acoustical Society of America 2005 — All rights reserved 7 1 iranenrl In arleuin4a mfnn AAICI nrrler Y 1d911151 rinu,nlnarlarl 11M/91)11 740 PIA Cinnla ricer Iiranea nnlu Cnnuinn and natu,nrkinn nrnhihiterl ANSI 512.9-2005/Part 4 Table 1 — Relation between sound exposure level and sound exposure for a constant sound level of 60 dB. T LAE(period) (dB) EA(period) (Pa2s) T LAE(period) (dB) EA(period) (Pa2s) 1 s 60.0 0.0004 1 h 95.6 1.44 1 min 77.8 0.024 24 h 109.4 34.6 NOTE A day -night sound exposure of 10 Pats corresponds to a nominal day -night average sound level of 55 dB. A day night average sound level of 65 dB corresponds to a nominal total day -night sound exposure of 100 Pa2s. 7.2 Adjustments to general environmental sound Research has shown that frequency -weighting A, alone, is not sufficient to assess sounds characterized by tonality, impulsiveness, very fast onset rates, or strong low -frequency content. Also, research has shown that frequency -weighting A, alone, under -predicts the community response to aircraft noise and to weekend daytime noise. To predict the long-term response of a community to sounds with some of those special characteristics, sources, or times of occurrence, an adjustment factor is used to multiply the sound exposure or an adjustment in decibels is added to the A -weighted sound exposure level. Annex H contains a bibliography of reports and articles describing the technical basis of the assessment and prediction methods of this Part 4. Sound exposure and sound exposure level as discussed in 7.1.1.1 and 7.1.2.1 are descriptors for characterizing the environmental sound from individual acoustical events. Frequency weighting A is used for all sound sources except (1) high-energy impulsive sounds for which frequency -weighting C is used, and (2) sounds with strong low -frequency content. Adjusted sound exposure is the quantity used in this Standard to assess sounds without and with special characteristics with respect to the potential community response. For general environmental sounds without special characteristics (i.e., sounds assessed by the method of 7.1), adjusted sound exposure is numerically equal to A -weighted sound exposure. For sounds with special characteristics, sources, or times of occurrence, the calculation of adjusted sound exposure or adjusted sound exposure level is performed as described below. The adjusted exposure method of presentation is described in 7.2.1, the left-hand column below. The adjusted level method of presentation is described in 7.2.2, the right-hand column below. 7.2.1 Adjusted exposure method 7.2.2 Adjusted level method 7.2.1.1 Adjusted sound exposure 7.2.2.1 Adjusted sound exposure level For any sound except high-energy impulsive sound For any sound except high-energy impulsive sound or sounds having strong low -frequency content, adjusted sound exposure Nj is given by the sound or sounds having strong low -frequency content, adjusted sound exposure level LN/ is given by the exposure E1 for the i-th single -event sound sound exposure level LE, for the i-th single -event multiplied by the adjustment factor K; for the j-th sound plus the level adjustment K1 for the j-th type type of sound, as given in Table 2. of sound, as given in Table 2. In mathematical notation, In mathematical notation, Nj = K1E1. (4a) LAIj= LE -i+ Kj. (4b) 8 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Equations to convert between adjusted sound exposure, in pascal -squared seconds, and adjusted sound exposure level, in decibels, are: LNj=10Ig(Nj/poTo) = 10 Ig(Nj / To) + 94 0.1(LNj —94) N1 = (T0)10 where —10 Ig(po) = 94 dB and To is the reference time of 1 s. (5a) (5b) 7.2.1.2 Adjusted total sound exposure During a time period of interest such as daytime, the adjusted total sound exposure N(period), in pascal -squared seconds, is the sum of the adjusted sound exposures Nu from each individual event i of I events, for each source of sound j of J sources during the stated time period. In mathematical notation, J N(period) i=i jE N1j . (6a) j=1 The stated time period may be of any duration such as one daytime period for one day or for any number of days up to 365 days of a year. Furthermore, the adjusted sound exposure Nu for the i-th event may be for any one source j or a combination of sources. In equation (6a), sounds without special characteristics are included with an adjustment factor of 1 as shown in Table 2. 7.2.2.2 Adjusted time -average sound level During a time period of interest such as daytime, the adjusted time -average sound level LN(period), in decibels, is calculated from the adjusted sound exposure levels LN from each individual event i of I events, for each source of sound j of J sources during the stated time period. In mathematical notation, I J 0.1 L LN(period) = 10 Ig [(T0 / T) E E 10 Nib ] .(6b) i=1 j=1 The stated time period T, in seconds, may be of any duration such as one daytime period for one day or for any number of days up to 365 days of a year. Furthermore, the adjusted sound exposure level LNC for the i-th event may be for any one source/ or a combination of sources. In equation (6b), sounds without special characteristics are included with a level adjustment of 0 as shown in Table 2. For an averaging time period T in seconds, equations to convert adjusted total sound exposure in pascal -squared seconds and adjusted time -average sound level in decibels are: LN(period) = 10 Ig (N(period) / p0 T0) — 10 Ig(T / TO ) (7a) = 10 Ig (N(period) / T) + 94 0.1(L N(period) _ (T)10N(period)-94) (7b) © Acoustical Society of America 2005 — All rights reserved 9 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 7.2.1.3 Adjusted total day -night sound exposure Adjusted total day -night sound exposure is similar to total day -night sound exposure, but includes the adjustment factors described in Table 2. Adjusted nighttime sound exposures are weighted by a factor of 10. The mathematical formulation of adjusted total day -night sound exposure Ndn is similar to that for total day -night sound exposure described in 7.1.1.3. 7.2.2.3 Adjusted day -night average sound level Adjusted day -night average sound level is similar to day -night average sound level, but includes the level adjustments described in Table 2. Ten decibels are added to adjusted nighttime sound exposure levels. The mathematical formulation of adjusted day -night average sound level LNdn is similar to that for day -night average sound level described in 7.1.2.3. For a time period Tdn of 24 h or 86,400 s, equations to convert adjusted day -night average sound level LNdn in decibels and adjusted total day -night sound exposure Ndn in pascal -squared seconds are: LNdn = 10 Ig(Ndn / p1T0) — 10 Ig(Tdn / T0) = 10Ig(Ndn /T0)+44.6 Ndn = (T0 )100.1(L Ndn —44.6) where —10 Ig( /4, ) — 10 Ig(Tdn/TO) = 94 — 49.4 = 44.6 dB, and To = 1 s. (8a) (8b) 10 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 nnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Table 2 — Adjustment factors and level adjustments for assessment of all types of environmental sounds. Sound source Kj Kj = l O Ig(K1 ) (dB) Condition Factor Type Symbol Value without special characteristics general broadband sound (e.g., road traffic) K 1 0 regular impulsive Ki 3 5 highly impulsive Ki 16 12 ... high-energy impulsive see Annex B Special characteristics KR 1 0 R < 15 dB/s rapid onset rate R KR 101.1 Ig(R/15) 11 Ig(R/15) 15 <_ R < 150 dB/s KR 12.6 11 R >_ 150 dB/s tonal Kt 3 5 see Annex C strong low -frequency content see Annex D KA 1 0 DNL<55 Sources aircraft KA 10*Ig(DNL-55) DNL-55 55<DNL<60 KA 3 5 DNL>60 Time of Day nighttime KN 10 10 Day of the Week weekends, daytime Kw 3 5 NOTE 1 If more than one special characteristic adjustment applies to a given single sound source such as a fan, only the largest adjustment shall be applied. Time -of -day and day -of -the -week adjustments are always included in addition to other adjustments, if any. NOTE 2 Each adjusted sound exposure N1 is calculated from its corresponding sound exposure level LAB./ and adjustment factor Kj according to 0.1(LAEij-94) N;j = (Kj I(T0)(1O )] • (9) NOTE 3 Each adjusted sound exposure level LNij is calculated from its corresponding sound exposure level and level adjustment Kj according to LNij = LAEij + K j . (10) NOTE 4 If sounds are not audible at the location of interest, then the concepts of Clause 6 apply and the adjusted sound exposure for those sounds shall not be included in the total. NOTE 5 The assessment method for essentially continuous sounds with strong low -frequency content shall not be applied unless the time -average C -weighted sound level exceeds the A -weighted sound level by at least 10 dB. NOTE 6 Normally, the onset rate is measured. Annex E provides an approximate method to calculate the onset rate for low-flying airplanes. NOTE 7 If highly impulsive sounds occur at a rate greater than about 20 per second, then the sounds usually are not perceived as distinct impulses and no adjustment shall be applied. If the rate is regular and greater than 30 per second, then a tone will be perceived and a tonal adjustment may be required. If the rate is irregular and greater than 20 per second, then the highly impulsive sounds will appear to merge into a broadband noise -like sound and no adjustment shall be applied. © Acoustical Society of America 2005 — All rights reserved 11 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d91f151 Onuinlnnrlarl 11M/91)11 740 PIA Cinnla near Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 8 Reporting assessments of environmental sounds and prediction of long- term community annoyance response 8.1 Use of A -weighted sound exposure and day -night average sound level If the acoustical environment includes only sounds having no special characteristics, then adjusted sound exposure is numerically equal to the sound exposure. All reporting then shall be in terms of A - weighted day -night average sound level or A -weighted sound exposure. If the acoustical environment includes any combination of sounds having special characteristics, then the numerical description of the total acoustical environment shall be reported in terms of adjusted sound exposure or adjusted sound exposure level. This procedure is required because adjusted sound exposure and adjusted sound exposure level are not measured quantities. 8.2 Assessment of environmental sounds A measurement or calculation of the (adjusted) total sound exposure or time -average sound level shall be used to assess environmental sounds. To predict or measure the (adjusted) total sound exposure or time -average sound level during a time period of interest, (adjusted) sound exposures shall be summed over the duration of the stated time period, typically, for some hour of the day, all day, all night, or a combination of the day -night sound or (adjusted) day -night sound exposure. For example, for an airport, factory, or highway, one might measure or calculate the annual average total day -night sound exposure or annual average adjusted total day -night sound exposure on an average day by summing the total sound exposure or adjusted total sound exposure throughout the year using equations (la) or (6a), respectively, and then dividing by 365. NOTE The user of this Standard can employ these methods for shorter periods of time, but they should report this change and not attempt to predict percent highly annoyed using Clause 8.3 or Annex F, since the Annex F data all represent long-term situations 8.3 Prediction of long-term annoyance response of communities Annual average (adjusted) total day -night sound exposure or annual average (adjusted) day -night average sound level is needed to predict the long-term annoyance response of a community. Table F.1 in Annex F may be used to predict the percentage of a population that is likely to be highly annoyed by the environmental sound with that annual average (adjusted) total day -night sound exposure or that annual average (adjusted) day -night average sound level. 8.4 Reporting Reporting shall include the following: a) the stated time period (e.g., daytime, 1600 to 1700 hours); b) the day or days included in the time average; c) the adjusted time -period total sound exposure or adjusted time -period time -average sound level; d) a description of the sound source or sources included in the total time period; e) a description of the measurement or prediction site; 12 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d91f151 flnu.nInnrlarl 11M/9f111 740 PIA Cinnla near Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 f) a description of any procedures used in accordance with Clause 7 and Annex A to correct for contamination by background sound and a description of the background sound; and g) the results of the prediction of long-term annoyance response of the community. NOTE The stated time period may be for any duration such as one daytime period for one day or for any number of days up to 365 days of a year. Furthermore, the sound exposure or adjusted sound exposure, EAJ or N1, for the j-th source, may be for any one source or a combination of sources. © Acoustical Society of America 2005 — All rights reserved 13 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Annex A (informative) Adjustments for background sound A.1 Introduction A.1.1 General Analysis of the annoyance generated by any given source of community noise is usually based on the assumption that the given source is the primary source of noise, and that the annoyance is not influenced by the presence (or absence) of sounds from other sources. For example, airports or roadways are often assessed as if they were the only source of sound. Because there almost always is noise from more than one source, two questions arise: 1) When does the amplitude of the sound from other sources become sufficient in magnitude to modify the annoyance generated by the source under evaluation? 2) Under what circumstances does the presence of sound from one source alter the annoyance caused by another source? A.1.2 Background sound Background noise is defined in ANSI S1.1 as "the total of all sources of interference in a system used for the production, detection, measurement, or recording of a signal, independent of the presence of the signal." For the purposes of this annex, background sound is the total of all sounds produced by sources other than the one for which the annoyance response is being evaluated. The amplitude of the background sound can be continuous or time -varying. Background sound may be produced by a variety of sources. A.1.3 Background sound situations There are at least two situations when background sound may influence or alter the presumed relation between annoyance and a physical measure of the sound for a given type of noise: 1) Masking is present when the threshold of detection of one sound is raised by the presence of another (masking) sound. Masking may be of varying degree, with complete masking resulting in the inaudibility (and resulting absence of annoyance) of the sound signal under evaluation. Given the time varying nature of many community sounds and their differences in spectral composition, the degree of masking is difficult to determine in most situations unless the differences between the time -average sound levels of the different sources are at least 20 dB. NOTE A masking analysis requires comparison of sound pressure levels in different frequency bands. Sounds having similar A -weighted sound levels may have quite different spectral content. Hence, it is impossible to determine the degree of masking from A -weighted sound levels. 2) The presence of sound from one source may alter an evaluation of the annoyance of the sound from another source. For example, at an outdoor music concert, one might be mildly annoyed by the noise from an aircraft flyover occurring during an intermission, but be highly annoyed by a similar 14 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 flnu.nlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 noise intrusion during the musical performance, even though the background sound levels during the intermission and performance are the same. Alternatively, one might ask whether the presence of intrusive sounds from one source alters the annoyance resulting from another intermittent sound, even though no masking of sounds may occur. (An example of this situation might be the evaluation of aircraft noise at a location exposed to noise from trains.) NOTE The influence of interactions between sound sources, outlined in the alternative situation above, is usually difficult to determine or is unknown, and is ignored in the analysis given in this annex. A.2 Mathematical development A.2.1 Single -event sounds For single -event sounds, Nu is the adjusted sound exposure produced by a discrete event i and sound type j. KB;; is the background sound adjustment factor for event i and sound type j. In the absence of noise from other sources, KB equals 1. In the presence of noise from other sources KB may vary from 1 to 0. With complete masking from other sources, KB = 0. Background sound adjustments are equivalent to changes in the noise adjustment factor KB as a consequence of masking by other sound sources. A.2.2 Continuous, or near -continuous, sounds and single -event sounds For continuous, or near -continuous, sounds, time -average, A -weighted sound level is symbolized by LAcont during the stated averaging time T. Consider a situation where there are two sources of single -event sound [for example, (1) trains for which the adjusted sound exposures are N1, and (2) aircraft for which the adjusted sound exposures are N21] and one source of continuous sound. The total adjusted sound exposure NT for the three sources over time duration T is determined from 11 NT = E (Nl )(KBl i }+ i=1 12 E (N2i)(KB2i) 1=1 [100.1(LAcont —94)IJ (T)(KBcont (A.1) NOTE 1 This 3 -source example may be expanded to include any number of different sources of single -event or continuous sounds. NOTE 2 11 is the number of trains and 12 is the number of aircraft during time duration T. For the situation where the single -event sounds for each source occurring during a time period of duration T are nearly equal (i.e., the sound exposure levels and maximum A -weighted sound levels are nearly equal), equation (A.1) is replaced by © Acoustical Society of America 2005 — All rights reserved 15 1 iranenrl In arlauin4a mfnn AAICI nrrlar Y 1d911151 nnu.nlnarlarl 11M/91)11 740 PIA Cinnla Ticar Iiranea nnlu Cnnuinn and natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 NT = (I1)(Ni / )(KB1;) + (12)(N21 )(KB2/) + [io 0.1(LAcont—94)1 10 • A.3 Background sound adjustment situations (A.2) There are three groups of situations where background sound adjustments may need to be considered. A.3.1 Situations having little need for background sound adjustments A.3.1.1 Maximum single -event sound level much greater than the sound level of the continuous sound source When the maximum A -weighted sound levels of individual noise events from two sources are at least 15 dB greater than the time -average A -weighted sound level of the continuous sound source, and the number of individual noise events is not large (so that the probabilities of individual noise events from the two sources occurring at the same time are small), then there is little need for background sound adjustment to the sound exposures from the individual noise events. Hence, in this situation, background sound adjustment factors KB1; and KB2; in equations (A.1) and (A.2) remain equal to 1.0. A.3.1.2 Few individual noise events The impact of sound from individual sources on the background sound adjustment factor for continuous sound KBcoflt is negligible if there are only a few individual noise events from the sources. In this situation there is little likelihood of KBcoflt changing from a value of 1. A.3.1.3 Many individual noise events When there are many noise events from individual sound sources, separately or in combination, the total adjusted sound exposure from these sources is likely to be much larger than the sound exposure for the continuous noise. In this situation the contribution from the continuous sound source will have little effect on the total adjusted sound exposure. A.3.2 Situations where background sound adjustments may be needed A.3.2.1 Maximum single -event sound level nearly equal to the sound level of the continuous sound source When the maximum A -weighted sound levels of individual single -event sounds from either of the two example sources, or both, are within 10 dB of the time -average A -weighted sound level, background sound adjustments KB, and/or KB2 are needed because of partial masking. In this situation, a value of KB, and/or KB2 equal to 1 may be appropriate. A.3.2.2 Many individual noise events from either of both sound sources When the maximum A -weighted sound levels of individual noise events from the two example sound sources are of the same order of magnitude and when the number of noise events from one or both 16 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 flnu.nlnnrlarl 11M/91)11 7.40 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natu.nrkinn nrnhihitarl ANSI 512.9-2005/Part 4 sources is large, background sound adjustments KB1 or KB2, or both, are needed because of partial masking of one individual noise event by another. In this situation, a value of KB1 and/or KB2 equal to 1/2 may be appropriate. A.3.3 Situations where significant background sound adjustments are needed When the maximum A -weighted sound levels of individual noise events are at least 10 dB less than the time -average A -weighted sound level for the continuous sound, partial or complete masking of the sound from the individual events is likely to occur. In this situation, a value of zero for the background sound adjustments of KB1 and KB2 is recommended. A.3.4 Guidance on the development of background sound adjustment factors Appropriate background sound adjustment factors may be developed from considerations of the level of the A -weighted signal-to-noise ratio 13 equal to (S+N)/N, i.e., the combined level of the A -weighted signal plus the A -weighted noise, minus the level of the A -weighted noise. In situations where the spectra of the sounds from the sound sources are vastly different, the levels of signal-to-noise ratios determined from octave- or one -third -octave -band sound pressure levels should be examined instead of A -weighted sound levels to establish background sound adjustment factors KBik for each j-th source and spectral band k. These spectral signal-to-noise levels are then examined to determine how the sound exposures in question should be combined in the calculation of total sound exposure. Recommended values for KB;k are: KBjk = 1, for /3>_ 20 dB (A.3) KBjk = /3 / 20, for 0 < /3 <_ 20 dB KBjk = 0, for /3 = 0 . © Acoustical Society of America 2005 — All rights reserved (A.4) (A.5) 17 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 flnu.nlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnls, Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Annex B (normative) High-energy impulsive sounds B.1 Introduction The procedure in this annex is based on a 1996 study by the National Research Council, Committee on Hearing, Bioacoustics, and Biomechanics (CHABA); see Ref. 14. It conforms with ISO 1996:1- 2003 (Ref. 6) which is also based, in part, on the CHABA study. NOTE The CHABA study presented two methods to assess high-energy impulsive sounds. One method is amenable to the concept of adjusted sound exposure and is presented in this annex. The other method is not amenable to the concept of adjusted sound exposure. B.2 Fundamental descriptor For single -event, high-energy impulsive environmental sounds, the fundamental descriptor is C -weighted sound exposure Ec or C -weighted sound exposure level LCE. B.3 Measurement C -weighted sound exposure (or C -weighted sound exposure level) shall be measured or predicted as if it had been measured by a microphone in a "free -field" and at least 15 m from any large reflecting object other than the ground which should be grass or a field. B.4 Calculation of adjusted sound exposure level for high-energy impulsive sounds from C -weighted sound exposure level For each single event, adjusted sound exposure level LNE for high-energy impulsive sounds shall be calculated from the C -weighted sound exposure level LCE according to LNE = 2 LCE -93 dB for LCE >_100 dB (B.1) LNE = 1.18 LCE— 11 dB for LCE < 100 dB The two relations intersect at a C -weighted sound exposure level of 100 dB. B.5 Calculation of adjusted sound exposure level from C -weighted sound exposure level Adjusted sound exposure N for high-energy impulsive sounds is related to adjusted sound exposure level LNE according to 0.1(L —94) N = 10 NE (B.2) 18 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl Substituting equation (B.1) in equation (B.2) yields 0.1(2LCE - 93 - 94) N = 10 0.1(2LCE -187) = 10 for LcE > 100. N = 10 = 10 0.1(1.18LCE -11- 94) 0.1(1.18LCE -105) for LcE < 100. ANSI 512.9-2005/Part 4 (B.3a) (B.3b) B.6 Calculation of adjusted sound exposure level from C -weighted sound exposure C -weighted sound exposure level LCE is related to C -weighted sound exposure E0 by LCE = 94+10 Ig (EC / 1) . (B.4) Substituting equation (B.4) in equation (B.3) yields the relation between adjusted sound exposure N and C -weighted sound exposure Ec for high-energy impulsive sounds as 0.1{2[94 + 10 Ig(EC /1)]- 187} N = 10 = 10[Ig (EC /1)2 +0.1] = (EC )2(10+0.1) = 1.2589(EC )2 for Ec>-3.9811. N = 10 0.1{1.18[94 + 10 Ig(EC /1)] -105} = 10[Ig (EC /1)1.18 +0.592] _ (EC )1.18(10+0.592) - = 3.908(EC )1.18 for Ec < 3.9811. B.7 Use of adjusted sound exposure (B.5a) (B.5b) Adjusted sound exposures determined by the procedures in B.4, B.5, or B.6 are used in equation (6a) to provide the contributions from high-energy impulsive sounds to the total adjusted sound exposure. © Acoustical Society of America 2005 — All rights reserved 19 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Annex C (informative) Sounds with tonal content The test for the presence of a prominent discrete -frequency spectral component (tone) typically compares the time -average sound pressure level in some one -third -octave band with the time -average sound pressure levels in the adjacent two one -third -octave bands. For a prominent discrete tone to be identified as present, the time -average sound pressure level in the one -third -octave band of interest is required to exceed the time -average sound pressure level for the two adjacent one -third -octave band by some constant level difference. The constant level difference may vary with frequency. Possible choices for the level differences are: 15 dB in low -frequency one -third -octave bands (25-125 Hz), 8 dB in middle -frequency bands (160-400 Hz), and 5 dB in high -frequency bands (500-10,000 Hz). NOTE 1 The above guidance is from Annex C of Part 3 of ANSI S12.9. Part 3 of ANSI S12.9 also contains guidance on the measurement of one -third -octave -band sound pressure levels. NOTE 2 ANSI S1.13 Annex A presents more accurate methods for determining the presence of prominent discrete tones using narrow -band analysis. 20 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl Annex D (informative) Sounds with strong low -frequency content D.1 Introduction ANSI 512.9-2005/Part 4 Sounds with strong low -frequency content engender greater annoyance than is predicted from the A - weighted sound level. The additional annoyance may result from a variety of factors including (1) less building sound transmission loss at low frequencies than at high frequencies and (2) increased growth in subjective loudness with changes in sound pressure level at low frequencies. In addition, environmental sound pressure levels in excess of 75 to 80 dB in the 16, 31.5, or 63 -Hz octave bands may result in noticeable building rattle sounds. Rattle sounds can cause a large increase in annoyance. The methods in this annex may be used to assess environmental sounds with strong low - frequency content. D.2 Analysis factors Analysis of sounds with strong low -frequency content is based on the following three factors: 1) Generally, annoyance is minimal when octave -band sound pressure levels are less than 65 dB at 16, 31.5, and 63 -Hz midband frequencies. However, low -frequency sound sources characterized by rapidly fluctuating amplitude, such as rhythm instruments for popular music, may cause annoyance when these octave -band sound pressure levels are less than 65 dB. 2) Annoyance grows quite rapidly with sound pressure level at very low frequencies. A "squared" function represents this phenomenon in this annex. 3) Annoyance to sounds with strong low -frequency content is virtually only an indoor problem. Although windows and house walls have significant high -frequency sound transmission loss, sounds in the 16, 31.5 and 63 -Hz octave bands pass through these structures to the interior with relative ease. The low -frequency sound pressure level within these structures is nearly equal to the outdoor sound pressure level because the minimal sound transmission loss of the windows and walls often is offset by modal resonance amplification in enclosed rooms. D.3 Applicability The procedures in this annex only should be applied to essentially continuous sounds with strong low - frequency content. NOTE In accordance with NOTE 5 to Table 2, the adjustment factors for essentially continuous sounds with strong low -frequency content shall not be applied unless the time -average C -weighted sound level exceeds the A - weighted sound level by at least 10 dB. © Acoustical Society of America 2005 — All rights reserved 21 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d91f151 flnuinInnrlarl 11M/9f111 740 PIA Cinnla near Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 D.4 Descriptor The descriptor for sounds with strong low -frequency content is the summation of the time -mean - square sound pressures in the 16, 31.5, and 63 -Hz octave bands. The result is the low -frequency, time -mean -square sound pressure pi F . The corresponding low -frequency sound pressure level is symbolized by LLF. D.5 Adjusted sound exposures for sounds with strong low -frequency content D.5.1 Adjusted sound exposure level from low -frequency sound pressure level For sounds with strong low -frequency content, adjusted sound exposure level LNE is calculated from low -frequency sound pressure level LLF by LNE= 2(LLF — 65) + 55 + 10 Ig(T / 1) (D.1) = 2LLF — 75 + 10 Ig(T / 1) where T is the time duration of interest, in seconds, over which the low -frequency sound is present. The factor of 2 in equation (D.1) accounts for the rapid increase in annoyance with sound pressure level at low frequencies. Equation (D.1) also accounts for the additional annoyance from rattles that begins when the low -frequency sound pressure level exceeds 75 dB. D.5.2 Adjusted sound exposure from low -frequency sound pressure level For sounds with strong low -frequency content, adjusted sound exposure N is calculated from low - frequency sound pressure level LLF by means of 0.1(2LLF-75-94) N = T[10 ] = T[10 0.1(2LLF-169)] D.5.3 Adjusted sound exposure from low -frequency sound pressure (D.2) For sounds with strong low -frequency content, adjusted sound exposure N also may be calculated from the time -mean -square low -frequency sound pressure pi F by use of equation (D.2) as 0.1(2LLF-169) N = T[10 ] = T[100.1{2[10Ig(plF/1)+94]-169}1 = T[10 0.1[10Ig(pF/1)+19]1 = (T)(pLF)(101.9 ). 22 (D.3) © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinu.nlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 D.6 Use of adjusted sound exposure Adjusted sound exposures calculated by means of equations (D.2) or (D.3) are used in equation (6a) to provide the contributions to the total adjusted sound exposure from sounds with strong low - frequency content. D.7 Noise -induced rattles There is evidence that noise -induced rattles are very annoying and not accounted for by direct measurement of the audible sound. The evidence suggests that rattle annoyance may be independent of the number or duration of events. To prevent the likelihood of noise -induced rattles, the low -frequency sound pressure level should be less than 70 dB. © Acoustical Society of America 2005 — All rights reserved 23 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Annex E (informative) Onset rate for airplane flybys Onset rate for the sound from a low-flying airplane may be estimated if the height of the airplane above ground, lateral offset of the calculation location from the nominal ground track, groundspeed, and the A -weighted sound exposure level of the airplane flyby are known. The following equation provides an empirical estimate for use in Table 2 of the onset rate R in decibels per second for an airplane flying past some location. R = 3.7 + exp( -1.1668 — 0.000563z —0.000177y + 0.0045v (E.1) +0.02884LAE ) where z = aircraft height above the elevation of the calculation location (metres); y = lateral offset from the nominal aircraft track to the calculation location (metres); v = aircraft groundspeed (nautical miles per hour or knots); and LAE = calculated or measured A -weighted sound exposure level at the calculation location (decibels). As an example, assume that z = 90 m, y = 150 m, v = 500 knots, and LAE = 115 dB. Equation (E.1) yields R = 79.1 dB/s. The applicable formula in Table 2 indicates that the corresponding level adjustment for this rapid onset rate is given by 11 Ig(79.1/15) = 7.9 dB. In U.S. customary units of feet for aircraft height and lateral offset, equation (E.1) becomes R = 3.7 + exp( -1.1668 — 0.00185z —0.000581y + 0.0045v +0.02884LAE ) 24 (E.2) © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Annex F (informative) Estimated percentage of a population highly annoyed as a function of adjusted day -night sound level F.1 Introduction In 1978, T.J. Schultz published a relation between the percentage of a population expressing high annoyance to aircraft, road traffic and railway noise and the corresponding A -weighted day -night sound level. A few years later, Kryter (see Bibliography [6]) argued that the community response to transportation noise could not be represented by one single curve: for equal day -night levels, the percentage of respondents being highly annoyed by aircraft noise was higher, and the percentage of respondents being highly annoyed by railway sounds was lower than that for road traffic noise. Revised curves published in 1994 by Finegold et al. were derived from a wider set of data than the set used by Schultz. The revised data show aircraft, road traffic and railway noise separately since, as noted earlier by Kryter, there was a systematic difference among them, at least at high sound pressure levels. Recently Miedema and Vos have concluded yet another meta-analysis and found somewhat similar systematic differences. F.2 The Dose -response function The dose -response relationship for road traffic noise obtained by Finegold et al. estimates the percentages of highly annoyed respondents that were slightly lower than the percentages from the Schultz curve. The dose -response relationship for road traffic noise obtained by Miedema and Vos, however, estimates percentages of highly annoyed respondents that are slightly higher than the percentages from the Schultz curve. The average of the curves obtained by Finegold et al. and by Miedema and Vos virtually coincides with the Schultz curve. Therefore, for simplicity and historical significance, the Schultz curve is taken as the curve to define the percentage of a population that is highly annoyed (%HA) to road traffic noise as a function of the day -night sound level, Ldn determined for the free field condition (i.e., the reflection at the building is not taken into account). The solid line in Figure F.1 shows the Schultz curve. About 90% of the grouped results from the various field surveys would fall within the two broken lines. The equation of the Schultz curve shown in Figure F.1 is given by %HA = 100 / [1 + exp(10.4 — 0.132 Ldn)] © Acoustical Society of America 2005 — All rights reserved (F.1) 25 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Percent highly annoyed (%) 100 90 80 70 60 50 40 30 20 10 0 40 50 60 70 80 Adjusted A -weighted day -night level (dB) 0.3 3.2 32 320 3200 Approximate total adjusted day -night sound exposure Figure F.1 — Percentage of respondents highly annoyed by road traffic sounds, as a function of the A -weighted day -night level About 90% of the raw data points on which the average curve is based fall within the two dashed lines. NOTE This dose -response relationship also can be used to assess the community annoyance response for other sources if the relevant source adjustments suggested in this document have been applied. F.3 Qualifications to the dose -response function F.3.1 Equation (F.1) is applicable only to long-term environmental sounds such as the yearly average. F.3.2 Equation (F.1) should not be used with shorter time periods like weekends, a single season, or "busy days." Rather, the annual average or some other long-term period should be used. F.3.3 Equation (F.1) is not applicable to a short-term environmental sound such as from an increase in road traffic due to a short -duration construction project. F.3.4 Equation (F.1) is only applicable to existing situations. 26 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 F.3.4.1 In newly created situations, especially when the community is not familiar with the sound source in question, higher community annoyance can be expected. This difference may be equivalent to up to 5 dB. F.3.4.2 Research has shown that there is a greater expectation for and value placed on "peace and quiet" in quiet rural settings. In quiet rural areas, this greater expectation for "peace and quiet" may be equivalent to up to 10 dB. F.3.4.3 The above two factors are additive. A new, unfamiliar sound source sited in a quiet rural area can engender much greater annoyance levels than are normally estimated by relations like equation (F.1). This increase in annoyance may be equivalent to adding up to 15 dB to the measured or predicted levels. For acoustical environments that include sounds with special characteristics, the annual -average adjusted day -night sound level LNdn should be used in equation (F.1) instead of the non -adjusted annual -average day -night sound level Ldn. Table F.1 provides annual -average adjusted day -night sound levels at 1 -dB increments and the corresponding total adjusted day -night sound exposures and percentages of highly annoyed. © Acoustical Society of America 2005 — All rights reserved 27 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Table F.1 - Annual -average adjusted A -weighted day -night sound levels and corresponding total adjusted day -night sound exposures and percentages of a population highly annoyed Annual- average adjusted day -night sound level (dB) Total adjusted day -night sound exposure (Pa2s) Approximate total adjusted day -night sound exposure (Pa2s) Percentage highly annoyed (%) Annual- average adjusted day -night sound level (dB) Total adjusted day -night sound exposure (Pals) Approximate total adjusted day -night sound exposure (Pa2s) Percentage highly annoyed (%) 40 0.3 0.3 0.6 61 43.3 40 8.7 41 0.4 0.4 0.7 62 54.5 50 9.8 42 0.5 0.5 0.8 63 68.6 63 11.1 43 0.7 0.6 0.9 64 86.4 80 12.4 44 0.9 0.8 1.0 65 109 100 13.9 45 1.1 1 1.1 66 137 125 15.6 46 1.4 1.3 1.3 67 172 160 17.4 47 1.7 1.6 1.5 68 217 200 19.4 48 2.2 2 1.7 69 273 250 21.6 49 2.7 2.5 1.9 70 344 315 23.9 50 3.4 3.2 2.2 71 433 400 26.3 51 4.3 4 2.5 72 545 500 29.0 52 5.5 5 2.8 73 686 630 31.8 53 6.9 6.3 3.2 74 864 800 34.7 54 8.6 8 3.7 75 1088 1000 37.8 55 10.9 10 4.1 76 1369 1250 40.9 56 13.7 12.5 4.7 77 1724 1600 44.1 57 17.2 16 5.3 78 2170 2000 47.4 58 21.7 20 6.0 79 2732 2500 50.7 59 27.3 25 6.8 80 3440 3150 54.0 60 34.4 32 7.7 81 4330 4000 57.2 NOTE 1 The relationships in Table F.1 also apply for annual -average day -night sound levels of environmental sounds without special characteristics or unusual community response. NOTE 2 Table F.1 is applicable only to long-term environmental sounds such as the yearly average. NOTE 3 Table F.1 is not applicable to "busy days" such as an average for say 30 days selected from a year because those 30 days had many noise -producing events and the other 335 days had many fewer such events. NOTE 4 Table F.1 is not applicable to a short-term transient environmental sound such as from a short -duration construction project. NOTE 5 Table F.1 is not applicable if there is sound -induced building vibration or rattles. Some studies have shown sound - induced building vibration or rattles to increase the equivalent annoyance by at least 10 dB. (See also D.7.) 28 © Acoustical Society of America 2005 - All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d91f151 flnuinInnrlarl 11M/9f111 740 PIA Cinnla near Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Annex G (informative) Assessing the complaint potential of high -amplitude impulse noise G.1 Introduction Several decades of experience in handling noise complaints at military installations shows that substantive complaints typically result from the louder and/or more unusual events. Thus, a long-term average noise level metric arguably is not adequate alone to predict community complaint response, or indeed to protect against valid damage claims. A viable procedure is to supplement the long-term average (e.g. DNL) noise impact assessment procedure with risk criteria for community response in terms of complaints as a function of a single -event metric. Appropriate candidate metrics are suggested in Clause 4.1.1. This annex provides a method to assess the complaint risk from military high -amplitude impulse sound such as the sounds produced by artillery or tank gun fire, bombs, military explosives, and similar civilian sources.1 Historically, the peak level has been used with success to predict military blast noise complaints, though it does not account for the effect of event duration. Another candidate is the sound exposure level. For historical simplicity, the wide -band peak level is used in this annex. These risk criteria are only intended to be applied to blast noise events from large weapons such as artillery and tank guns and from fairly large explosions (approximately 0.1 to 100 kg). These sources exhibit considerable low frequency sound energy, with a sound exposure level spectrum that typically peaks in the range from 10 to 100 Hz. These noise complaint risk criteria should not be used for other sources of noise such as small arms noise and aircraft noise. G.2 Complaint criteria A set of risk criteria was developed by the Navy (Ref. 23) to guide decisions that balance risk of noise complaints against the cost or other consequences of canceling training or testing activity. These guidelines were based on records of complaints received, sound level measurements, sound level calculations, and balloon -suspended radiosonde meteorological soundings. The guidelines were also evaluated during a subsequent study (Ref. 26) and found to be a reliable method to predict complaints resulting from the firing of large guns. The risk criteria, presented in Table G.1, are expressed in terms of degree of complaint risk as a function of the value of the unweighted peak noise metric. G.3 Complaint risk prediction Large caliber weapons are very strong acoustic sources. The sound from firing these weapons can be easily audible at long distances, often as far as several tens of kilometers. Change in weather conditions can profoundly influence received noise levels. Sound propagation is influenced by vertical and horizontal profiles of values of atmospheric meteorological parameters such as temperature, 1 For purposes of this annex, the weight of charge should be, approximately, between 0.1 and 50 kg. © Acoustical Society of America 2005 — All rights reserved 29 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 flnu.nlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 humidity, wind speed and wind direction. Variation as large as 50 dB in received values of single -event noise metrics such as peak and SEL are routinely encountered (see for example Ref. 24). The criteria presented in Table G.1 are based on the correlation of degree of risk of noise complaints for known event levels. Useful prediction of complaint risk also must take into account the expected statistical variation in received single -event peak noise level due to weather. If one predicts the mean peak level for all expected event levels, the actual noise level will be higher than the predicted mean level for 50% of all expected events, and may be higher by as much as 25 dB. This affords rather limited protection against receiving noise complaints, since a 25 -dB change in event level can change complaint risk from low to high. On the other hand, basing risk of noise complaints on the maximum expected level would be far too conservative. An adequate procedure is to base assessment of complaint risk on a predicted exceedance level. As an example, consider PK15, the peak (unweighted) level that can be expected to be exceeded by 15% of expected blast noise events. A prediction of PK15 = 130 dB means that the risk of receiving a noise complaint would be expected to be high for 15% of all expected events. This strategy requires that the variance in received noise level due to weather effects are known, which is the case for blast noise from large guns. 30 Table G.1 — Complaint Risk Criteria Risk of Noise Complaints Large Caliber Weapons Noise Level (Unweighted Peak) Low < 115 Medium 115 — 130 High 130 — 140 Risk of physiological damage to unprotected human ears and structural damage claims > 140 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl Annex H (informative) Loudness -level weighting H.1 Introduction ANSI 512.9-2005/Part 4 The A -weighting filter can be replaced by the equal -loudness -level contours (Figure H.1) from ISO 226 (May 1987) as a dynamic filter that changes both with amplitude and with frequency. To approximate sound heard indoors, the sound is first filtered by a generalized house filter that is adjusted to approximate a window's slightly open condition—on the order of 5 cm (Figure H.2)2. This new method eliminates the need for the aircraft source adjustments in Table 2. Thus, with this new method, one can measure all transportation noise sources in a given situation. In effect, this new method provides a family of curves that vary systematically with sound frequency and level (Figure H.1). Schomer (2000) shows that the use of loudness -level weighting provides for much better correlation with subjective annoyance responses than does the A -weighting. This new method uses fast -time - weighted one -third -octave -band spectra sampled every 100 ms over the duration of an event such as an aircraft flyby. Fast -time weighting is used to approximate the integration time of human hearing. Each spectral band level is replaced by its corresponding phon level using an analytical representation of Figure H.1. These phon levels are summed over time and frequency on an energy basis to form the loudness -level -weighted sound exposure level (LLSEL). The analytical representation is given in Table H.1. H.2 The method A sound event such as the sound of an airplane flyby or a truck passby is analyzed into one -third - octave bands. Human hearing is such that short -duration sounds are not perceived to be as loud as long -duration sounds. To be perceived with full loudness, sound must be present for a duration that is longer than the integration time of the ear. Thus, in this procedure, the one-third octave band spectra are fast time weighted and sampled every 100 ms. The fast time weighting is used to approximate the integration time of the ear which data indicate lies between 25 ms and 250 ms. Since the time constant for fast -time -weighting is 125 ms, 100 ms is an adequate rate with which to sample the spectra. This forms a time -series of one -third -octave -band spectra. Equal -loudness -level contours are given in functional form in Table H.1 However, this method requires that the sound first be filtered by the house filter of Figure H.2 and as given in Table H.1. Then the analytical functions given in Table H.1 can be applied. The loudness -level functions and house filter in Table H.1 correspond to one -third -octave -band center frequencies from 20 Hz to 12,500 Hz. Each filtered one -third -octave -band sound pressure level (SPL) is assigned the phon level that corresponds to that frequency and level. For example, from Table H.1, a filtered one -third -octave - band SPL of 82 dB in the 125 -Hz band would be assigned a value of 80 phon since it corresponds to a phon level of 80. Similarly, a filtered one -third -octave -band level of 82 dB in the 31.5 -Hz band would be assigned a value of 51 phon. 2 The house filter simulates the Sound Transmission Loss (TL) of a typical house, in this case with windows open about 2 cm, when sound is transmitted from outdoors to indoors. © Acoustical Society of America 2005 — All rights reserved 31 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 The overall time -integrated phon level (LLSEL) is calculated from the time and frequency energy summation of the time -series of filtered one -third -octave band spectra. This time -series of 100 ms, filtered one -third -octave -band spectra is used to calculate the overall time- and frequency -summed phon level, LL, that is given by: LL =10Iog L.110 L10Li j 1 (H.1) where Luj is the phon level corresponding to the ith filtered one -third -octave band during the jth time sample. The quantity calculated by equation (H.1), LL, has been designated as the loudness -level -weighted sound exposure level (LLSEL). It is similar to the A -weighted sound exposure level (ASEL) except that instead of using a filter (A -weighting) that varies only with frequency, LLSEL uses a dynamic filter that varies with both SPL and frequency. Similarly, one can calculate loudness -level -weighted equivalent level (LL-LEQ) or loudness -level weighted day -night level (LL-DNL). 32 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl 130 120 .110 -a▪ 100 N 90 i 80 70 60 150 O _ 40 30 0 20 c' 10 0 -10 10 ANSI 512.9-2005/Part 4 100 1000 Frequency (Hz) 10000 Figure H.1 — Equal loudness level contours in phons from ISO 226-1987. The non -shaded area shows the frequency range where, approximately, a 10 -dB change in sound pressure level corresponds to a 10 -dB change in phon level. At low frequencies this relationship does not occur. For example, at 31 Hz, a 10 -dB change in sound pressure level corresponds to about a 20 -dB change in phon level. J H 0 M 0 0 x 35 30 - 25 20 - 15 10- 5 (1O "�`� c�0 �0 �h 0 0 00 00 <00 00 <00 00 00 00 `� L h O \q. �O � (oO 00 h Frequency (Hz) Figure H.2 — Generalized house TL for windows open on the order of 5 cm. © Acoustical Society of America 2005 — All rights reserved 33 1 iranenrl In arlauinka mfnn AAICI nrrlar Y 1d911151 flnuinlnarlarl 11M/91)11 740 PIA Cinnla Ticar Iiranea nnlu Cnnuinn and natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Frequency 20 25 31 40 50 63 80 100 af 2.347 2.190 2.050 1.879 1.724 1.597 1.512 1.466 Lu 0.00561 0.00527 0.00481 0.00404 0.00338 0.00286 0.00259 0.00257 Tf 74.3 65 56.3 48.4 41.7 35.5 29.8 25.1 House TL 9 10 11 12 13.5 15 16.5 18 Frequency 125 160 200 250 315 400 500 630 af 1.426 1.394 1.372 1.344 1.304 1.256 1.203 1.136 Lu 0.00256 0.00256 0.00254 0.00248 0.00229 0.00201 0.00162 0.00111 Tf 20.7 16.8 13.8 11.2 8.9 7.2 6 5 House TL 18.75 19.5 20.25 21 21.75 22.5 23.25 24 Frequency 800 1000 1250 1600 2000 2500 3150 4000 af 1.062 1.000 0.967 0.943 0.932 0.933 0.937 0.952 Lu 0.00052 0 -0.00039 -0.00067 -0.00092 -0.00105 -0.00104 -0.00088 Tf 4.4 4.2 3.7 2.6 1 -1.2 -3.6 -3.9 House TL 24.5 25 25 25 25 25 25 25 Frequency 5000 6300 8000 10000 12500 af 0.974 1.027 1.135 1.266 1.501 Lu -0.00055 0 0.00089 0.00211 0.00489 Tf -1.1 6.6 15.3 16.4 11.6 House TL 25.65 26.35 27 27.65 28.35 Table H.1 - Coefficients for calculation loudness level from band sound pressure level. The table also includes the house filter characteristics shown in Figure H.2. For any band, loudness level is calculated from the respective band j sound pressure level, Li by: LL; = 4.2 + [af, (L, - Tf;)]/[1 + Lu, (L; - Tf,)] where LL; is the loudness level in the jth band. The house TL is included by modifying (H.2) to: LLQ = 4.2 + [af; (L; - TL; - Tf;)]/[1 + Lu, (L; - TL, - Tf;)] 34 (H.2) (H.3) © Acoustical Society of America 2005 - All rights reserved 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Bibliography NOTE The following references are available in the open literature or through the National Technical Information Service (NTIS). NTIS numbers are given at the end of each reference. General [1] Schultz, T.J. "Synthesis of social surveys on noise annoyance," J. Acoust. Soc. Am. 64(2), 337-405, August 1978. [2] Finegold, L.S., Harris, C.S, and von Gierke, H.E. "Community annoyance and sleep disturbance: Updated criteria for assessing the impacts of general transportation noise on people," Noise Control Eng. J., 42(1), 25-30, 1994 January -February. [3] Miedema, H.M.E., and Vos, H. "Exposure -response relationships for transportation noise," J. Acoust. Soc. Am., 104(6) 3432-3445, 1998. [4] Schomer, P.D. "Loudness -level weighting for environmental noise assessment," Acustica/Acta Acustica, 86(1), 49-61, 2000. [5] Schomer, P.D. "The importance of proper integration of and emphasis on the low -frequency sound energies for environmental noise assessment," Noise Control Engineering J., 52(1), 26-39, January/February 2004. [6] ISO 1996-1:2003 Acoustics—Description, measurement, and assessment of environmental noise—Part 1: Basic quantities and assessment procedures, Geneva, 2003. [7] U.S. General Accounting Office (GAO), Aviation and the Environment --Results From a Survey of the Nation's 50 Busiest Commercial Service Airports, GAO/RCED-00-222, Washington D.C., August 2000. [8] Hume, K.I., Morley, H.E., Sutcliffe, M.J., Smith, G.R., and Thomas. C.S. "What do the location of noise complaints and noise contours tell us about the pattern and level of disturbance around airports?", INTERNOISE 2005, Rio de Janeiro, Brazil, 07-10 August 2005. Impulsive sounds [9] Berry, B.F. and Bisping, R. "CEC joint project on impulse noise: Physical quantification methods," Proc. 5th Intl. Congress on Noise as a Public Health Problem, 153-158, Stockholm, 1988. [10] Borsky, P.N. "Community reactions to sonic booms in the Oklahoma City area: Vol. 1, Overview; Vol. 2, Data; Vol. 3, Questionnaires," USAF Aerospace Medical Research Laboratory Rep. AMRL-TR-65-37, Wright-Patterson Air Force Base, Ohio, 1965 (NTIS Vol. 1, AD613620; Vol. 2, AD625332; Vol. 3, AD637563). [11] Buchta, E. "A field study on annoyance caused by sounds from small firearms," J. Acoust. Soc. Am., 88(3), 1459-1467, September 1990. [12] Bullen, R.B., Hede, A.J., and Job, R.F.S. "Community reaction to noise from an artillery range," Noise Control Eng. J., 37(3), 115-128, 1991 November -December. © Acoustical Society of America 2005 — All rights reserved 35 1 iranenrl In arlauin4a mfnn AAICI nrrlar Y 1d91f151 flnuinInarlarl 11M/9f111 740 PIA Cinnla near Iiranea nnlu Cnnuinn and natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 [13] "Assessment of community response to high-energy impulsive sounds," Report of Working Group 84, Committee on Hearing, Bioacoustics and Biomechanics (CHABA), National Research Council, National Academy of Science, Washington, D.C., 1981 (NTIS ADA110100). [14] "Community response to high-energy impulsive sounds: An assessment of the field since 1981," Committee on Hearing, Bioacoustics and Biomechanics (CHABA), National Research Council, National Academy of Science, Washington, D.C., 1996 (NTIS PB 97-124044). [15] Kryter, K.D., Johnson, P.J., and Young, J.P. "Psychological experiments on sonic booms conducted at Edwards Air Force Base," USAF Contractor Report AF 49(638), USAF National Sonic Boom Evaluation Office, Arlington, Virginia, 1968 (NTIS AD689844). [16] Schomer, P.D., Wagner, L.R., Benson, L.J., Buchta, E., Hirsch, K.W., and Krahe, D. "Human and community response to military sounds: Results from field -laboratory tests of small -arms, tracked -vehicle, and blast sounds," Noise Control Eng. J., 42(2), 71-84, 1994 March -April. [17] Schomer, P.D., "New descriptor for high-energy impulsive sounds," Noise Control Eng. J., 42(5), 179-191, 1994 September -October. [18] Schomer P.D., and Wagner, L.R. "Human and community response to military sounds — Part 2: Results from field -laboratory tests of sounds of small arms, 25 -mm cannons, helicopters, and blasts," Noise Control Eng. J., 43(1), 1-13, 1995 January -February. [19] Siskind, D.E., Stachura, V.J., Stagg, M.S., and Kopp, J.W. "Structure response and damage produced by airblast from surface mining," Bureau of Mines Report of Investigations, Report Number RI 8485, U.S. Department of the Interior, Washington, D.C., 1980 (NTIS PB81- 148918). [20] Stachura, V.J., Siskind, D.E., and Engler, A.J. "Airblast instrumentation and measurement techniques for surface mine blasting," Bureau of Mines Report of Investigations, Report Number RI 8508, U.S. Department of the Interior, Washington, D.C., 1981 (NTIS PB81- 227118). [21] Vos, J. "On the level -dependent penalty for impulse sound," J. Acoust. Soc. Am., 88(2), 883- 893, August 1990. [22] Vos, J. "A review of research on the annoyance caused by impulse sounds produced by small firearms," Proc. INTER -NOISE 95, edited by Robert J. Bernhard and J. Stuart Bolton, Noise Control Foundation, Poughkeepsie, New York, 1995, Vol. II, pp. 875-878. [23] Pater, L. "Noise Abatement Program for Explosive Operations at NSWC/DL", presented at the 17th Explosives Safety Seminar of the DOD Explosives Safety Board, 1976. [24] Schomer, P.D. "Statistics of amplitude and spectrum of blasts propagated in the atmosphere," Journal of the Acoustical Society of America, 63(5), May 1978. [25] Siskind, D.E. "Vibrations and Airblast Impacts on Structures from Munitions Disposal Blasts," Proceedings, Inter -Noise 89, G.C. Maling, Jr., editor, pages 573 – 576, 1989. [26] CHPPM (Center for Health Promotion and Preventive Medicine) Environmental Noise Study No. 52-34-QK33-95, Results of Eastern Shore Vibration Monitoring, Aberdeen Proving Ground, Maryland, September 1993 -November 1994. 36 © Acoustical Society of America 2005 — All rights reserved 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d911151 rinuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl ANSI 512.9-2005/Part 4 Tone corrections [27] Kryter, K.D. Effects of Noise on Man, 2nd ed., Academic, New York, 1985. [28] Scharf, B., Hellman, R., and Bauer, J. "Comparison of various methods for predicting the loudness and acceptability of noise," Office of Noise Abatement and Control, U.S. Environmental Protection Agency, Washington D.C., August 1977 (NTIS PB81-243826). [29] Scharf, B. and Hellman, R. "Comparison of various methods for predicting the loudness and acceptability of noise, Part II, Effects of spectral pattern and tonal components," Office of Noise Abatement and Control, U. S. Environmental Protection Agency, Washington D.C., November 1979 (NTIS PB82-138702). [30] ANSI S1.13-2005 Annex A American National Standard Measurement of Sound Pressure Levels in Air, Annex A Identification and evaluation of prominent discreet tones. [31] Hellweg R.D., and Nobile, M. "Modification to procedures for determining discrete tones," INTER -NOISE 2002 paper 473, Dearborn, MI, August 2002. Sounds with strong low -frequency content [32] Broner N. and Leventhall, H.G. "Low frequency noise annoyance assessment by low frequency noise rating (LFNR) curves," J. Low Frequency Noise Vib., 2(1), 20-28, 1983. [33] Hubbard, H.H. and Shepherd, K.P. "Aeroacoustics of large wind turbines," J. Acoust. Soc. Am., 89(6), 2495-2508, June 1991. [34] Kelley, N.D., McKenna, H.E., Hemphill, R.R., Etter, C.L., Garrelts, R.L., and Linn, N.C. "Acoustic noise associated with the MOD -1 wind turbine: Its source, impact and control," Solar Energy Research Institute Technical Report, SERI TR -635-1166, February 1985 (NTIS DE85- 002947). [35] Scharf, B. and Hellman, R. "Comparison of various methods for predicting the loudness and acceptability of noise, Part II, Effects of spectral pattern and tonal components," Office of Noise Abatement and Control, U. S. Environmental Protection Agency, Washington D.C., November 1979, (NTIS PB82-138702). [36] Yeowart, N.S. and Evans, M.J. "Threshold of audibility for very low frequency pure tones," J. Acoust. Soc. Am., 55(4), 814-818, April 1974. © Acoustical Society of America 2005 — All rights reserved 37 1 iranenrl In erlauin4e mfnn AAICI nrrlar Y 1d91f151 flnuinInnrlarl 11M/9f111 740 PIA Cinnla near Iirnnee nnlu Cnnuinn enrl natuinrkinn nrnhihitarl 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnly Cnnuinn enrl natuinrkinn nrnhihitarl MEMBERS OF THE ASA COMMITTEE ON STANDARDS (ASACOS) P. D. Schomer, Chair and ASA Standards Director Schomer and Associates 2117 Robert Drive Champaign, IL 61821 Tel: +1 217 359 6602 Fax: +1 217 359 3303 Email: schomer at7,SchomerAndAssociates.com S. B. Blaeser, Standards Manger Standards Secretariat Acoustical Society of America 35 Pinelawn Rd., Suite 114E Melville, NY 11747 Tel: +1 631 390 0215 Fax: +1 631 390 0217 Email: asastds@aip.orq Ex Officio Members of ASACOS D. Neff, Chair, ASA Technical Council D. Feit, ASA Treasurer T.F.W. Embleton, Past Chair ASACOS C.E. Schmid, ASA Executive Director Representation S1, Acoustics J.P. Seiler, Chair, S1 ASA Representative, S1 G.S.K. Wong, Vice Chair, S1 ASA Alternate Representative, S1 Representation S2, Mechanical Vibration and Shock R.J. Peppin, Chair, S2 D.J. Evans, Vice Chair, S2 S.I. Hayek, ASA Representative, S2 B.E. Douglas, ASA Alternate Representative, S2 Representation S3, Bioacoustics R.F. Burkard, Chair, S3 ASA Representative, S3 C. Champlin, Vice Chair, S3 ASA Alternate Representative, S3 Representation S12, Noise R.D. Hellweg, Chair, S12 W.J. Murphy, Vice Chair, S12 B.M. Brooks, ASA Representative, S12 Vacant Alternate Representative, S12 ASA Technical Committee Representation A.P. Lyons, Acoustical Oceanography A.E. Bowles, Animal Bioacoustics G.E. Winzer, Architectural Acoustics C. Everbach, Bioresponse to Vibration and to Ultrasound M.D. Burkhard, Engineering Acoustics I. Lindevald, Musical Acoustics R.J. Peppin, Noise S.I. Madanshetty, Physical Acoustics B.W. Edwards, Psychological and Physiological Acoustics D.J. Evans, Signal Processing in Acoustics S. Narayanan, Speech Communication S.I. Hayek, Structural Acoustics and Vibration J. Zalesak, Underwater Acoustics U. S. Technical Advisory Group (TAG) Chairs for International Technical Committees P.D. Schomer, Chair, U. S. TAG, ISO/TC 43 V. Nedzelnitsky, Chair, U. S. TAG, IEC/TC 29 D.J. Evans, Chair, U. S. TAG, ISO/TC 108 1 iranenrl In arlauin4a mfnn AAICI nrrlar Y 1d911151 flnu.nlnarlarl 11M/91)11 740 PIA Cinnla Ticar Iiranea nnlu Cnnuinn and natuinrkinn nrnhihitarl ANSI S12.9-2005/Part 4 1 iranenrl In erlauinke mfnn AAICI nrrlar Y 1d911151 flnuinlnnrlarl 11M/91)11 740 PIA Cinnla Ticar Iirnnee nnly Cnnuinn enrl natuinrkinn nrnhihitarl Attachment D icntclarion 4 $1.00 THE NEWSPAPER WITH THE HILLSIDE SLANT Volume 84, issue 1G BayArevnity t wsGra Wessciers 401 A BOOMING SPORT Pickiebali games' Iroise could soon be a past racket New generation of equipment developed to lessen its frequency, pitch, overall acoustic burden. Page 3 JANE TYSKA — STAFF PHOTOGRAPHER Angie Perez, left, and Darlene Vendegna test out new quieter pickleball paddles during a demonstration put on Jan. 24 by USA Picklehail at Piedmont's Linda Beach courts. The "pop, pop, pop" that's become synonymous with pickleball may soon be a racket of the past with a new generation of equipment and technology specifically developed to lessen the frequency, pitch and overall acoustic burden of the booming sport. FRIDAY, FEBRUARY 2, 2024 BALL IN PIEDMONT, ELSEWHERE New, quieter equipment takes swing at Softer paddles, sound panels meant to cut acoustic signature in half, which should please axn By Katie Lauer Ictaiwr®B¢yurea neresgroup.com PIEDMONT >t The "pop, pop, pop" that's become synon- ymous with pickieball may soon be a racket of the past. At least, that's the lofty goal promised by a new generation of equipment and technology specifi- cally developed to lessen the frequency, pitch and overall acoustic burden of the booming sport. Rather than listen- ing to plastic -y staccato "thwacks," imagine slightly padded "thumps" when paddles and balls collide. News of this emerg- ing gear could be music to nonplayers' ears, especially as the fast-growing sport has sparked neighborhood clashes and legal battles in recent years. Across the Bay Area, complaints have popped up in Berkeley, San Francisco, Los Altos, Menlo Park, Walnut Creek, but res- idents and elected officials have continually struggled to craft solutions that re- solve pickleball's cacoph- onous soundtrack without shutting down the sport al- together. Carl Schmits, USA Pick- leball's managing direc- tor of facilities develop- ment and equipment stan- dards, said that as tennis courts, basketball courts and other spaces in com- munity parks were rapidly converted to meet the de- mand of pickieball players across the Bay Area, many of those changes happened without much research into how the game might in- crease the amount of noise and number of people in those spaces. Schmits said that's why Pickieball USA has been researching and investing in solutions with acoustic STAFF PHOTOS BY JANE TYSKA Carl Schmits, right, USA Pickleball's managing director of facilities development and equipment standards, demonstrates a new quieter pickieball racquet Jan. 24 at Pied- mont's Linda Beach courts. To the left is Eliot Arnold, the founder and chief executive officer of SLN/CR - a Kansas City -based startup that 'produces sound -absorbing panels. engineering firms for the past 18 months aiming to change the actual sound of the game and also help local communities under- stand how to best study and improve the acoustics of existing facilities be- fore installing additional courts. On Jan. 24, Schmits dem- onstrated a handful of new equipment specifically de- signed for quieter play at Piedmont's Linda Beach Pickieball Courts. That lo- cation was fitting, since players are already re- quired - or at least encour- aged - to only use equip- ment that's been certified in USA Pickleball's newly launched "Quiet Category" of products. Piedmont offi- cials have even printed out a color -coded list of accept- able paddles and balls to use at Linda Beach. Generally speaking, Schmits said certified "quiet" paddles can reduce the sound of contact from 90 decibels - roughly the volume of hairdryers and power tools - down to 80 decibels, which is closer to the noise levels measured on a busy downtown street or near a garbage disposal. He said this new genera- tion of gear also is meant to lower the pitch of the ball "pops," which can nega- tively impact players' hear- ing. earing. Since the launch of the first quiet paddles by OWL Sport in November, Schmits said cutting the acoustic signature of the sport in half is possible, especially when combined with other interventions, such as fabric sheaths that cover louder paddles and sound -absorbing panels de- signed with innovative car- bon nanofibers and poly- mer cores that can be in- stalled along fences around pickieball courts. "It's a difficult engineer- ing challenge to squeeze any more noise out," Schmits said, explaining why Pickleball USA is also researching ways that arti- ficial intelligence and other technologies as — sess and west of gameplzy `lintels category (of quieter ucts) that we created help address very situations' Eliot Arnold, the fader and chief executive al& - cer of SLN/CR -• a Z n- sas City -based manly ant ___ - in additive is 112e !km* tquipsest b aianst■i- tie ed- objective cera ant real --time brasses et the lsa ii marts w72 be vial in the worts vat turn. as well as its as add is. pr ay As the sport grow -s. there's going to be mare need to collect informa- tion and analyze informa- tion - not just going off people's opinions.' Arnold said. "Instead of having a neighbor call (about noises. can we build a system that alerts the community, law enforcement or Parks and. Rec.?" Justin Long, the city of Alameda's director of its Recreation and Park De- partment, is one of many city administrators who are increasingly trying to find new tools and data to un- AY AREA NEWS GROUP 3 e problem derstand — let alone miti- gate — just how much noise pickleball games create. Since isolating which activities and people are contributing to noise com- plaints is often difficult, Long said information from product research and acoustic baseline studies will make balancing the perspectives of pickleball players and neighbors liv- ing near their courts easier for local decision -makers. "(This kind of data is) helping us navigate the conversation between op- posing sides," Long said San. 24. "We want to make sure that we're providing activities for everyone in the community, but how do you balance such opposing forces? It invites conflict because in every city, land is (at) a premium. We can't just expand every sport." Even though this new type of equipment may present additional chal- lenges down the line — especially since new gear can often be more expen- sive and inaccessible, Long said he supports any extra resources that civic leaders like him can use to be good stewards for everybody. "The good thing is that the dialogues are happen- ing," he said. "It doesn't need to happen in court." Darlene Ven- degna, left, and Angie Perez test out new quieter picklebali paddies with Connie Fong and Rick Schiller, both at right, during a Jan. 24 demonstration put on by USA Pickiebali at the Linda Beach courts in Piedmont. Attachment E kAO" r t �• ir