1、Designation: E 1704 95 (Reapproved 2002)Standard Guide forSpecifying Acoustical Performance of Sound-IsolatingEnclosures1This standard is issued under the fixed designation E 1704; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 The guide covers the development of criteria for theacoustical performance of a broad variety of acoustical
3、 enclo-sures by identifying information necessary to unambiguouslydescribe acoustical performance. This guide is not a standardASTM specification for a sound-isolating enclosure.1.2 Excluded from the scope of this guide are technicalconsiderations for enclosure design that do not pertain directlyto
4、acoustical performance.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior
5、 to use.2. Referenced Documents2.1 ASTM Standards:C 423 Test Method for Sound Absorption and Sound Ab-sorption Coefficients by the Reverberation Room Method2C 634 Terminology Relating to Environmental Acoustics2E 336 Test Method for Measurement of Airborne SoundInsulation in Buildings2E 413 Classifi
6、cation for Rating Sound Insulation2E 596 Test Method for Laboratory Measurement of theNoise Reduction of Sound-Isolating Enclosures22.2 ANSI Standards:ANSI S1.4 Specification for Sound Level Meters3ANSI S3.1 Maximum Permissible Ambient Noise Levelsfor Audiometric Test Rooms3ANSI S3.6 Specification f
7、or Audiometers3ANSI S12.31S12.35 Methods for Determining the SoundPower Levels of Machines and Equipment32.3 ISO Standard:ISO 37413745 AcousticsMethods for Determining theSound Power Levels of Machines and Equipment32.4 Government Standard:29 CFR 1910.95 Occupational Noise Exposure Occupa-tional Saf
8、ety and Health Administration42.5 Other Standard:VDI 2711 Schallschutz durch Kapeslung Verein DeutscherIngeireure, Beuth Verlag GmbH, Berlin German NoiseControl by the Use of Enclosures53. Terminology3.1 Definitions:3.1.1 Standard definitions of acoustical terms may be foundin Terminology C 634.3.2
9、Definitions of Terms Specific to This Standard:3.2.1 A-weighted sound pressure levelsound pressurelevel measurements made with the A-weighting filter appliedas defined in ANSI S1.4, denoted LPAin this guide.3.2.2 C-weighted sound pressure levelsound pressurelevel measurements made with the C-weighti
10、ng filter appliedas defined in ANSI S1.4, denoted LPCin this guide.3.2.3 enclosurea structure, usually free-standing, whichsubstantially or completely encloses a given space or object.This does not include barrier walls, partitions within a building,or other partial structures.3.2.4 enclosure-genera
11、ted noisesound created by the op-eration of the enclosure systems, such as lighting and ventila-tion.3.2.5 level reductionfor the purposes of this guide, thearithmetic difference between sound pressure levels at aspecific location before and after the installation of the enclo-sure, expressed in dec
12、ibels.3.2.6 level reduction specificationspecification of theacoustical performance of an enclosure by stating the reductionin sound pressure level caused by the enclosure.3.2.7 personnel enclosurean enclosure designed to keepsound energy from personnel or equipment therein. Examplesof personnel enc
13、losures include but are not limited to audio-metric booths, in-plant offices, broadcast booths, and acousticaltest chambers.3.2.8 pre-installation sound pressure levelsthe soundpressure levels, as a function of frequency, that are present1This guide is under the jurisdiction of ASTM Committee E33 on
14、 EnvironmentalAcoustics and is the direct responsibility of Subcommittee E33.03 on SoundTransmission.Current edition approved June 15, 1995. Published August 1995.2Annual Book of ASTM Standards, Vol 04.06.3Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 1
15、0036.4Available from the Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.5Available from Beuth Verlag GmbH, Burggrafenstrasse 4-7, 1000 Berlin 30.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.prior
16、 to the installation of the enclosure. In most cases this isdetermined by measuring the ambient sound pressure levels inthe host area but in some cases, such as new construction, thesound pressure levels must be predicted.3.2.9 sound pressure level specificationspecification ofthe acoustical perform
17、ance of an enclosure by stating themaximum sound pressure levels that shall exist after installa-tion.3.2.10 source enclosurean enclosure designed to keepsound energy from personnel or equipment on the outside.Such applications include, but are not limited to, equipmentsilencing, secure communicatio
18、ns, music practice, and acous-tical testing.4. Summary of Guide4.1 An explanation of the determination and subsequentspecification of acoustical performance of sound-isolatingenclosures is presented.4.2 Two types of specifications are described in this guide.The recommended method (sound pressure le
19、vel specification)is to specify the maximum permissible sound pressure levelsthat may be present after installation of the enclosure. Thealternate method (level reduction specification) is to specify theenclosures level reduction.4.3 The type of specification selected depends largely on theenclosure
20、 application and the data available. A sound pressurelevel specification usually applies to a specific site, while thelevel reduction specification may have broader application.Also, the sound pressure level specification is more appropriatewhere specific sound pressure levels are required, while th
21、elevel reduction specification reflects a more general interest inamounts of noise level reduction.4.4 Some guidance is provided in Appendix X1 on selectinga specification type based on the enclosure application and theinformation available.4.5 Substantial guidance is given on the essential acoustic
22、aldata that must be compiled.4.6 A non-mandatory model specification Appendix X2 isincluded that embraces both specification types. It also servesas a guide for identifying and gathering information necessaryto the manufacturer for designing the enclosure.5. Significance and Use5.1 This guide can be
23、 used to produce a specification for theacoustical performance of an enclosure.5.2 This guide is intended for those familiar with basicconcepts of acoustics.5.3 Although this guide provides detailed guidance in mat-ters relating to specification of acoustical enclosures, it is not asubstitute for th
24、e experience and judgment of an acoustical ornoise control professional.5.3.1 This guide calls for measurements common withinacoustical practice.5.3.2 The more critical the performance requirements of theenclosure, the more the user should consider seeking theservices of an acoustics or noise contro
25、l professional.5.4 The specifying of a sound-isolating enclosure has threesequential steps:5.4.1 Determine the sound pressure levels that exist atspecific locations prior to the introduction of the enclosure,NOTE 1In the case of new construction, the sound pressure level isoften estimated from the s
26、ound power levels of noise-emitting equipmentand a general description of the acoustical properties of the environment.5.4.2 Determine the maximum permissible sound pressurelevels that must exist at the same locations after the introduc-tion of the enclosure, and5.4.3 Determine the required enclosur
27、e level reduction. Therequired isolation is related to the difference between the soundpressure levels before and after the introduction of the enclo-sure.5.5 Many specifications are for multiple enclosures orenclosures with multiple functions, or both. It is beyond thescope of this guide to provide
28、 detailed guidance for everypossible combination. Separate specifications for each source-enclosure-receiver combination should be used in such a case.5.6 The type of specification that should be selected de-pends both on the purpose of the enclosure and how crucial itsperformance is. In general:5.6
29、.1 If exceeding a particular maximum permissible soundpressure level spectrum would render the enclosure unsuccess-ful, a sound pressure level specification should be used.5.6.1.1 This guide assigns all phases of acoustical design aredelegated to the supplier. Compliance is usually more easilyverifi
30、ed than with the level reduction method.5.6.2 If the criteria for the success of the enclosure are lessstringent or not related to a specific maximum permissiblespectrum, a level reduction specification may be used.6. Recommended Specifications6.1 The sound pressure level specification specifies the
31、maximum permissible sound pressure levels that may existeither inside or outside the enclosure after installation. Pre-installation sound pressure levels must also be presented.6.1.1 Maximum sound pressure levels should be specified inone-third-octave bands whenever possible to allow a detailedfit t
32、o the requirements. Octave band sound pressure levels areappropriate where the noise spectrum is broad band and free ofprominent tones.6.1.2 The desired post-installation sound pressure level mayalso be described by a single number descriptor, such asA-weighted sound pressure level or NC or RC ratin
33、gs.6In thisevent the pre-installation one-third-octave band sound pressurelevels at or around the installation site shall also be provided.NOTE 2Other single number ratings for noise may also be available.For further information see ASHRAE Handbook.66.1.3 Measured sound pressure levels are preferred
34、. Whennot available, such as in the case of new construction, thefollowing information is usually considered an acceptablesubstitute to allow estimation of sound pressure levels:6.1.3.1 The rated or measured sound power level (heredenoted LW) of equipment and,6ASHRAE Handbook, Fundamentals, Chapter
35、7, American Society of Heating,Refrigerating and Air Conditioning Engineers, Atlanta, Georgia.E 170426.1.3.2 A description of the host environment, including therelative locations of sources of noise, personnel, and theenclosure. Some loss of accuracy should be expected.6.1.4 Inaccurate measurement
36、of sound pressure levels canresult from unsteady or intermittent sources of noise duringmeasurement, changes in site conditions after measurement(for example, significant sources of noise arising betweenmeasurement and installation), strong low frequency content(LPCLPA 15), and general inexperience
37、with acousticalmeasurements.6.1.5 Maximum permissible sound pressure levels are oftenprescribed for particular applications by standards or regula-tory documents. A short list includes, but is not limited to,hearing conservation regulations, architectural specifications,human comfort, speech intelli
38、gibility, speech privacy, andacoustical test standards. Common specific cases are cited inAppendix X1.6.1.6 The maximum permissible interior or exterior soundpressure levels should not be exceeded with all sources ofenclosure-generated noise in normal operation.6.2 The level reduction specification
39、identifies the minimumpermissible level reduction to be provided by the enclosure.This type specification is often used by a buyer who hasalready determined the isolation needed to meet his soundpressure level requirements. Using this type of specificationwithout such analysis could result in unacce
40、ptable results.6.2.1 Level reduction I(f) can be approximated as follows:If! 5 L12 L21 SFwhere:L1= pre-installation sound pressure level in a given band,L2= post-installation sound pressure level in a given band,andSF = safety factor.6.2.1.1 The safety factor helps ensure compliance by ac-counting f
41、or unforeseen complications due to changes in siteconditions, or unusual acoustical interactions of the enclosureand the space. The more critical the successful performance ofthe enclosure, the larger the selected safety factor should be.Typical values are:Not Critical SF = 0 dBModerate SF = 3 dBCon
42、servative SF = 6 dBNOTE 3In practice safety factor size varies with frequency as well aswith importance. The user should consider applying stringent safetyfactors only in bands where they are most needed in order to avoidover-designing the enclosure.6.2.1.2 The introduction of the enclosure may sign
43、ificantlyalter the sound field near the noise source, increasing both theeffective value of L1and the required level reduction. Thiseffect is important when either the physical volume or thesound absorption coefficients of the surfaces around the noisesource are reduced by a factor of two or more. I
44、n this case,detailed information on noise source and its pre-installationsurroundings should accompany the specification. In addition,a larger safety factor should be considered.6.2.2 The level reduction of enclosures is typically quanti-fied by the manufacturer in laboratory prototype testing. Nois
45、ereduction (NR) is measured per Test Method E 596, and noiseisolation class (NIC) is calculated per Classification E 413. Forthe purposes of this guide, noise reduction data are anacceptable equivalent for level reduction.6.2.2.1 Custom designs are typically not tested, due to cost.6.2.2.2 The actua
46、l enclosure being specified may differ incertain particulars from prototypes tested.6.2.2.3 Because of variations in manufacturing materialsand methods and changes in test standards, test results shouldbe no older than five years.6.2.2.4 Laboratory noise reduction data obtained in accor-dance with T
47、est Method E 596 in prototype testing are oftenaccepted as performance verification.6.2.3 An enclosure may provide the required level reductionwithout achieving a particular sound pressure level spectrum inthe protected space. As an example, sound pressure levelsinside an enclosure will be considera
48、bly higher when theenclosure is located in a high ambient noise area.7. Other Noise Control Properties of Enclosures7.1 Vibration IsolationThe effectiveness of an enclosurecan be compromised by structure-borne noise bypassing theacoustical barrier through adjacent building structures. Enclo-sures sh
49、ould be isolated from adjacent structures by means offlexible connections.7.1.1 Vibrations that can be felt by the hand are an indica-tion that measurements of vibration levels are necessary.NOTE 4In typical installations, structure-borne vibration treatmentsare part of the enclosure. Special cases, for example, broadcast studios,generally require measurement or analysis of structure-borne vibrationpatterns of the host environment prior to specification, or both, whereapplicable.NOTE 5The Lameasurement and treatment of structure-borne vibra-tion are difficult.
