1、AMERICAN NATIONAL STANDARDMETHODS FOR DETERMININGTHE INSERTION LOSS OFOUTDOOR NOISE BARRIERSAccredited Standards Committee S12, NoiseStandards SecretariatAcoustical Society of America120 Wall Street, 32nd FloorNew York, New York 10005-39ANSI/ASA S12.8-1998ANSI/ASAS12.8-1998Reaffirmed by ANSI April 2
2、1, 2008Reaffirmed by ANSI on June 24, 2007 Reaffirmed by ANSI on June 24, 2007 Reaffirmed byANSI onMarch 13, 2003Reaffirmed by ANSI May 28, 2013 The American National Standards Institute, Inc. (ANSI) is the na-tional coordinator of voluntary standards development and the clear-inghouse in the U.S. f
3、or information on national and internationalstandards.The Acoustical Society of America (ASA) is an organization of sci-entists and engineers formed in 1929 to increase and diffuse theknowledge of acoustics and to promote its practical applications.American National StandardMethods for Determining t
4、he Insertion Lossof Outdoor Noise BarriersSecretariatAcoustical Society of AmericaApproved 27 April 1998American National Standards Institute, Inc.AbstractThis Standard presents three methods for determining the insertion loss of outdoor noise barriers. Themethods are direct BEFORE and AFTER measure
5、ments; indirect BEFORE measurements at anequivalent site; and indirect predictions of BEFORE sound levels. Indirect BEFORE measurementsand indirect BEFORE prediction methods require direct measurements of AFTER sound levels.Measurements of acoustical descriptors use sound sources naturally present a
6、t a site, controlled naturalsound sources, or controlled artificial sound sources. Within prescribed limits, the receiver location andatmospheric, ground, and terrain conditions may be chosen based on the objectives for determination ofbarrier insertion loss. Examples are provided for worksheets tha
7、t may be used for data acquisition andanalysis.ANSI S12.8-1998AMERICAN NATIONAL STANDARDS ON ACOUSTICSThe Acoustical Society of America (ASA) provides the Secretariat for AccreditedStandards Committees S1 on Acoustics, S2 on Mechanical Vibration and Shock,S3 on Bioacoustics, and S12 on Noise. These
8、committees have wide represen-tation from the technical community (manufacturers, consumers, and general-interest representatives). The standards are published by the Acoustical Society ofAmerica through the American Institute of Physics as American National Stan-dards after approval by their respec
9、tive standards committees and the AmericanNational Standards Institute.These standards are developed and published as a public service to providestandards useful to the public, industry, and consumers, and to Federal, State,and local governments.Each of the Accredited Standards Committees operating
10、in accordance with pro-cedures approved by American National Standards Institute (ANSI) is responsiblefor developing, voting upon, and maintaining or revising its own standards. TheASA Standards Secretariat administers committee organization and activity andprovides liaison between the Accredited St
11、andards Committees and ANSI. Afterthe standards have been produced and adopted by the Accredited StandardsCommittees, and approved as American National Standards by ANSI, the ASAStandards Secretariat arranges for their publication and distribution.An American National Standard implies a consensus of
12、 those substantially con-cerned with its scope and provisions. Consensus is established when, in thejudgment of the ANSI Board of Standards Review, substantial agreement hasbeen reached by directly and materially affected interests. Substantial agreementmeans much more than a simple majority, but no
13、t necessarily unanimity. Consen-sus requires that all views and objections be considered and that a concertedeffort be made towards their resolution.The use of American National Standards is completely voluntary. Their existencedoes not in any respect preclude anyone, whether he or she has approved
14、thestandards 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 anytime. The procedures of the American National Standards Institute require thataction be
15、 taken periodically to reaffirm, revise, or withdraw this Standard.Standards SecretariatAcoustical Society of America120 Wall Street, 32nd FloorNew York, New York 10005-3993USATelephone: 11 212 248 0373Telefax: 11 212 248 0146E-mail: asastdsaip.org 1998 by the Acoustical Society of America. This Sta
16、ndard may not be reproduced inwhole or in part in any form for sale, promotion, or any commercial purpose, or any purposenot falling within the provisions of the Copyright Act of 1976, without prior written permissionof the publisher. For permission, address a request to the Standards Secretariat of
17、 theAcoustical Society of America.ContentsPageForeword . ii0 Introduction . 11 Scope . 12 Normative references 23 Definitions 24 Methods . 35 Sound sources and source equivalence 56 Acoustical environment 77 Instruments . 98 Measurements 109 Computations . 1210 Test Report . 17AnnexesA Effects of at
18、mospheric conditions 18B Worksheet forms . 19C Example computation of the insertion loss of an outdoor noisebarrier 25Tables1 Wind classes 42 Cloud cover classes 93 Adjustment for background noise contribution 14Figures1 Flow chart illustrating the choice of method to determine theinsertion loss of
19、an outdoor noise barrier 42 Reference microphone positions . 73 Flow chart illustrating computation of insertion loss for an outdoornoise barrier . 13iForewordThis Foreword is for information only and is not an integral part of American NationalStandard Methods for Determining the Insertion Loss of
20、Outdoor Noise Barriers, ANSIS12.8-1998.This American National Standard supersedes the previous version published asANSI S12.8-1987.This Standard contains three informative annexes.This Standard was developed under the jurisdiction of Accredited Standards Com-mittee S12, Noise, which has the followin
21、g scope:Standards, specifications, and terminology in the field of acoustical noisepertaining to methods of measurement, evaluation, and control, includingbiological safety, tolerance, and comfort, and physical acoustics as related toenvironmental and occupational noise.At the time this Standard was
22、 submitted to Accredited Standards Committee S12,Noise, for final approval, the membership was as follows:P. D. Schomer, ChairB. M. Brooks, Vice ChairA. Brenig, SecretaryAcoustical Society of America . P.D.SchomerW. J. Galloway (Alt.)Air-Conditioning and Refrigeration Institute ARI . S.WangS. Sander
23、s (Alt.)Air Movement and Control Association, Inc. AMCA M.StevensE. W. Neitzel (Alt.)Aluminum Company of America ALCOA S.I.RothAmerican Academy of Otolaryngology, Head and NeckSurgery, Inc. G.A.GatesL. A. Michael (Alt.)American College of Occupational Medicine P.J.BrownsonJ. Satalof (Alt.)American I
24、ndustrial Hygiene Association AIHA L.H.RoysterJ. F. Meagher (Alt.)American Otological Society. R.F.NauntonAmerican Society of Heating, Refrigerating, andAir-Conditioning Engineers ASHRAE . H-SPeiJ. L. Heldenbrand(Alt.)American Speech-Hearing-Language Association ASHA . J.D.RoysterM. E. Thompson(Alt.
25、)Audio Engineering Society, Inc. M.R.ChialD. Queen (Alt.)Bruel Telephone: 11212 248 0373; Fax 11 212 248 0146.iiiAmerican National StandardMethods for Determiningthe Insertion Loss ofOutdoor Noise Barriers0 IntroductionDetermining the insertion loss provided by outdoornoise barriers is often difficu
26、lt. In many cases, thedifficulty results from the absence of sound levelsmeasured at a site before barrier installation, orthe inability to estimate accurately the before-in-stallation sound levels. Lack of standard methodsfor determining barrier insertion loss may lead toincorrectly performed (or p
27、oorly documented)computations and prevent independent evaluationof techniques and results.1 Scope1.1 This Standard adopts insertion lossthe dif-ference between acoustical levels before and aftera noise-barrier installationas the basis for evalu-ating the acoustical effectiveness of an outdoornoise b
28、arrier. Methods are provided to determinethe insertion loss of outdoor noise barriers at se-lected receiver locations and under conditions ofinterest.1.2 This Standard covers insertion loss determi-nation, by measurement or by the combination ofmeasurement and prediction, for outdoor noisebarriers o
29、f all types. Sound sources at a site maybe those that are naturally present, controllednatural sound sources, or controlled artificialsound sources. Preferred acoustical descriptorsare time-average, A-weighted sound level, A-weighted sound exposure level, or octave-bandsound pressure level. Other ac
30、oustical descriptorsof the BEFORE and AFTER sound are not pre-cluded.1.3 Standardized receiver locations or measure-ment conditions are not prescribed. Measured in-sertion losses apply only for the stated conditionsand are not to be generalized to represent otherconditions, sites, receiver locations
31、, or soundsources.1.4 This Standard may be used for routinechecking of the insertion loss of an outdoor noisebarrier, or for engineering or diagnostic evalua-tions. The methods of the Standard may be usedin situations where a barrier is to be installed, orhas already been installed.1.5 This Standard
32、 does not present methods forcomparing the insertion loss of outdoor noise bar-riers at different sites, nor does it specifically ad-dress sound transmission loss through a barrier.While comparisons of the insertion loss of outdoornoise barriers at different sites or extrapolations toother condition
33、s may be possible, such compari-sons or extrapolations are not within the scope ofthis Standard.1.6 Reliable and repeatable results may be ex-pected when the distances between all receiversand their closest and strongest sound sources (orclosest point of approach for mobile soundsources) are within
34、70 m. The methods of theStandard may be applied for other conditions, butthe experimental uncertainties likely will increase,perhaps substantially.1.7 This Standard presents two methods for in-directly determining the level of the BEFOREsound. The two methods are (1) by measurementat a second site t
35、hat is equivalent to the desiredsite prior to installation of the barrier, or (2) by pre-diction of the BEFORE sound levels. Equivalencehere is in terms of sound-source characteristics,receiver locations, and terrain, atmospheric, andground conditions. The Standard presents prin-ciples, not procedur
36、es, for assessing sound-source, atmospheric and terrain equivalence, aswell as for choosing a model to predict the level ofBEFORE sound.1.8 This Standard presents a method to deter-mine a lower bound to the insertion loss whenbackground noise prevents clear measurement ofthe source sound level at a
37、receiver location. Inmany applications, reporting a barrier insertionloss for a given receiver location as equal to orgreater than X dB is sufficient. This Standard alsopresents a method to determine the total experi-mental uncertainty associated with the barrier in-sertion loss.1.9 Because of many
38、factors affecting the soundlevels at receiver locations, it may not be possibleto determine the insertion loss of an outdoor noisebarrier for conditions of interest.AMERICAN NATIONAL STANDARD ANSI S12.8-19981 1998 Acoustical Society of America2 Normative referencesThe following Standards contain pro
39、visions that,through reference in this text, constitute provisionsof this American National Standard. At the time ofapproval by the American National Standards In-stitute, Inc. (ANSI), the editions indicated werevalid. All Standards are subject to revision. Partiesto agreements based on this America
40、n NationalStandard are encouraged to investigate the possi-bility of applying the most recent editions of theStandards listed below. Information on the mostrecent editions is available from the ASA Stan-dards Secretariat.1 ANSI S1.1-1994, American National StandardAcoustical Terminology.2 ANSI S1.4-
41、1983 (R 1997), American NationalStandard Specification for Sound Level Meters.Amendment 1, ANSI S1.4A-1985.3 ANSI S1.11-1986 (R 1993), American NationalStandard Specification for Octave-Band and Frac-tional-Octave-Band Analog and Digital Filters.4 ANSI S1.15-1997/Part 1, American NationalStandard Me
42、asurement MicrophonesPart 1:Specifications for Laboratory Standard Micro-phones.5 ANSI S1.26-1995, American National Stan-dard Method for Calculation of the Absorption ofSound by the Atmosphere.6 ANSI S1.40-1984 (R 1997), American NationalStandard Specification for Acoustical Calibrators.7 ANSI S1.4
43、3-1997, American National Stan-dard Specification for Integrating-AveragingSound Level Meters.8 ANSI S12.9-1988/Part 1 (R 1993), AmericanNational Standard Quantities and Procedures forDescription and Measurement of EnvironmentalSoundPart 1.9 ANSI S12.9-1993/Part 3, American NationalStandard Quantiti
44、es and Procedures for Descrip-tion and Measurement of Environmental SoundPart 3: Short-Term Measurements with an Ob-server Present.10 ANSI/SAE J184a-1985, Qualifying a SoundData Acquisition System.3 DefinitionsFor the purposes of this Standard, the followingdefinitions apply. Definitions for related
45、 quantitiesare given in Part 1 of ANSI S12.9-1988 (R 1993)and in ANSI S1.1-1994.3.1 AFTER. Conditions or measurements at asite of interest where an outdoor noise barrier is inplace.3.2 atmospheric equivalence. Condition thatthe atmosphere at the BEFORE and AFTER sitesis acoustically similar in atmos
46、pheric absorption,wind, air temperature, and cloud cover.3.3 background noise level. Sound level orsound pressure level at a reference or receiverposition, without the sound source of interest inoperation. Unit, decibel (dB).NOTE Generally, background noise level shouldbe measured in terms of the ac
47、oustical descriptor forcalculation of barrier insertion loss.3.4 BEFORE. Conditions, measurements, orpredictions at a site before installation of an out-door noise barrier or any other site changes.3.5 controlled artificial sound source. Soundsource that is controlled in position, height aboveground
48、, output power, spectral content, and direc-tivity.3.6 controlled natural sound source. Testsound source taken from the population of naturalsound sources.NOTE As an example for highway traffic, a con-trolled natural sound source could be one or moretest trucks.3.7 equivalent site. For receiver posi
49、tions of in-terest, a site selected to determine BEFOREacoustical levels by the indirect measured methodand having terrain, ground, atmospheric, andsound-source conditions equivalent to those at thesite where an outdoor noise barrier is installed.3.8 ground equivalence. Condition that theground surfaces at the BEFORE and AFTER siteshave the same ground-surface classification.3.9 ground impedance. At a specified fre-quency, complex quotient of sound pressure bythe normal component of particle velocity directedinto the surface
