ASTM_E_2611_-_09.pdf

Designation:E261109Standard Test Method forMeasurement of Normal Incidence Sound Transmission ofAcoustical Materials Based on the Transfer Matrix Method1This standard is issued under the fixed designation E2611;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the use of a tube,fourmicrophones,and a digital frequency analysis system for themeasurement of normal incident transmission loss and otherimportant acoustic properties of materials by determination ofthe acoustic transfer matrix.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 to use.2.Referenced Documents2.1 ASTM Standards:2C634 Terminology Relating to Building and EnvironmentalAcousticsE90 Test Method for Laboratory Measurement of AirborneSound Transmission Loss of Building Partitions andElementsE1050 Test Method for Impedance and Absorption ofAcoustical Materials Using a Tube,Two Microphones anda Digital Frequency Analysis System2.2 ISO Standards:ISO 140-3 AcousticsMeasurement of Sound Insulation inBuildings and of Building ElementsPart 3:LaboratoryMeasurement of Airborne Sound Insulation of BuildingElements33.Terminology3.1 DefinitionsThe acoustical terminology used in this testmethod is intended to be consistent with the definitions inTerminology C634.3.1.1 reference planean arbitrary section,perpendicular tothe longitudinal axis of the tube that is used for the origin oflinear dimensions.Often it is the upstream(closest to the soundsource)face of the specimen but,when specimen surfaces areirregular,it may be any convenient plane near the specimen.3.1.2 sound transmission coeffcient,(dimensionless)ofa material in a specified frequency band,the fraction ofairborne sound power incident on a material that is transmittedby the material and radiated on the other side.5WtWiwhere:Wtand Wi=the transmitted and incident sound power.3.1.3 sound transmission loss,TLof a material in a speci-fied frequency band,ten times the common logarithm of thereciprocal of the sound transmission coefficient.The quantityso obtained is expressed in decibels.TL5 10 log10SWiWtD5 10 log10S1D3.1.3.1 DiscussionIn this standard the symbol TLnwill beapplied to sound which impinges at an angle normal to the testspecimen,as opposed to an arbitrary or random angle ofincidence.3.2 Symbols:c=speed of sound,m/s.=density of air,kg/m3.f=frequency,hertz,(Hz).G11,G22,etc.=auto power spectra(autospectrum)of theacoustic pressure signal at microphone locations 1,2,and soon.G21,G32,etc.=cross power spectrum(cross spectrum)ofthe acoustic pressure signals at location 2 relative to location 1,3 relative to 1,and so on.In general,a complex value.H21,H31,etc.=measured transfer function of the acousticpressure signals at location 2 relative to location 1,3 relative to1This test method is under the jurisdiction ofASTM Committee E33 on Buildingand Environmental Acoustics and is the direct responsibility of SubcommitteeE33.03 on Sound Transmission.Current edition approved March 1,2009.Published March 2009.DOI:10.1520/E2611-09.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 1,and so on.In general,a complex value.Note that H11ispurely real and equal to 1.HI,HII=calibration transfer functions for the microphonesin the standard and switched configurations,respectively.See8.4.Hc=complex microphone calibration factor accounting formicrophone response mismatch.H21,H31,etc.=transfer function of two microphone signalscorrected for microphone response mismatch.In general,acomplex value.NOTE1In this context,the term“transfer function”refers to thecomplex ratio of the Fourier transform of two signals.The term“fre-quency response function”arises from more general linear system theory(1).4This test method shall retain the use of the former term.Users shouldbe aware that modern FFT analyzers might employ the latter terminology.j=21k=2f/c;wave number in air,m-1.NOTE2In general the wave number is complex where k=kr jki.kris the real component,2 f/c,and kiis the imaginary component of thewave num