ASTM_E_2235_-_04_2012.pdf

Designation:E223504(Reapproved 2012)Standard Test Method forDetermination of Decay Rates for Use in Sound InsulationTest Methods1This standard is issued under the fixed designation E2235;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.INTRODUCTIONThis test method is part of a set of methods used to evaluate the sound-insulating properties ofbuilding elements.It is intended for use in conjunction with methods for measuring the transmissionof sound through a partition or partition element in a laboratory or in a building.These methodsinclude the laboratory measurement of airborne sound transmission loss of building partitions andelements(Test Method E90),the measurement of sound isolation in buildings(Test Method E336),thelaboratory measurement of impact sound transmission through floors(Test Method E492),themeasurement of impact sound transmission in buildings(Test Method E1007),the measurement ofsound transmission through building facades and facade elements(Guide E966),and the measurementof sound transmission through a common plenum between two rooms(Test Method E1414).1.Scope1.1 This test method covers the measurement of sounddecay rate in rooms and the calculation of the sound absorptionof the room and its contents.The sound absorption so calcu-lated may be used in calculations in sound insulation testmethods.1.2 The method shall be used only in conjunction with othertest methods where the logarithm of the sound absorption isused in formulas.It is not sufficiently precise for use insituations where room sound absorption is to be used withouttaking logarithms.1.3 For laboratory measurements of the sound absorption ofmaterials and objects,Test Method C423 should be used.1.4 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:2C423 Test Method for SoundAbsorption and SoundAbsorp-tion Coefficients by the Reverberation Room MethodC634 Terminology Relating to Building and EnvironmentalAcousticsE90 Test Method for Laboratory Measurement of AirborneSound Transmission Loss of Building Partitions andElementsE336 Test Method for Measurement of Airborne SoundAttenuation between Rooms in BuildingsE492 Test Method for Laboratory Measurement of ImpactSound Transmission Through Floor-Ceiling AssembliesUsing the Tapping MachineE966 Guide for Field Measurements of Airborne SoundAttenuation of Building Facades and Facade ElementsE1007 Test Method for Field Measurement of TappingMachine Impact Sound Transmission Through Floor-Ceiling Assemblies and Associated Support StructuresE1414 Test Method for Airborne Sound Attenuation Be-tween Rooms Sharing a Common Ceiling Plenum1This test method is under the jurisdiction ofASTM Committee E33 on Buildingand Environmental Acoustics and is the direct responsibility of SubcommitteeE33.01 on Sound Absorption.Current edition approved April 1,2012.Published August 2012.Originallyapproved in 2003.Last previous edition approved in 2004 as E2235 041.DOI:10.1520/E2235-04R12.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.2 ANSI Standards:3S1.4 Specification for Sound-Level MetersS1.6 Standard Preferred Frequencies,Frequency Levels,andBand Numbers for Acoustical MeasurementsS1.11 Specification for Octave-band and Fractional-Octave-Band Analog and Digital Filters3.Terminology3.1 Definitions of the acoustical terms used in this testmethod are given in Terminology C634.3.2 Definitions of Terms Specific to This Standard:3.2.1 output interval,t;T;sof a real-time analyzer,thetime between successive outputs of sound pressure levelsduring a single decay measurement.4.Summary of Test Method4.1 Sound decay rate in rooms is a function of frequency someasurements are made in a series of frequency bands.Bandsof random electrical noise are used as signals to drive loud-speakers in the room until the sound pressure level reaches asteady state.When the sound is then turned off,the soundpressure level decays at a rate determined by the soundabsorption in the room.The decay rate is measured in eachfrequency band by measuring the slope of a straight line fittedto the average decay curve.The absorption of the room and itscontents is calculated from the Sabine formula:A 5 0.921Vdc(1)where:A=sound absorption,m2,V=volume