ASTM C423-2009a 用混响室法测定吸声及吸声系数的标准试验方法

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【英文标准名称】:StandardTestMethodforSoundAbsorptionandSoundAbsorptionCoefficientsbytheReverberationRoomMethod
【原文标准名称】:用混响室法测定吸声及吸声系数的标准试验方法
【标准号】:ASTMC423-2009a
【标准状态】:现行
【国别】:美国
【发布日期】:2009
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E33.01
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:acoustical;acoustics;decayrate;noise;noisereductioncoefficient;reverberationroom;Acousticaltests;Decayrates;Noisereductioncoefficient;Reverberationroommethod;Soundabsorbing/insulatingmaterials/applications
【摘要】:Measurementofthesoundabsorptionofaroomispartoftheprocedureforotheracousticalmeasurements,suchasdeterminingthesoundpowerlevelofanoisesourceorthesoundtransmissionlossofapartition.Itisalsousedincertaincalculationssuchaspredictingthesoundpressurelevelinaroomwhenthesoundpowerlevelofanoisesourceintheroomisknown.Thesoundabsorptioncoefficientofasurfaceisapropertyofthematerialcomposingthesurface.Itisideallydefinedasthefractionoftherandomlyincidentsoundpowerabsorbedbythesurface,butinthistestmethoditisoperationallydefinedin4.2.Therelationshipbetweenthetheoreticallydefinedandtheoperationallymeasuredcoefficientsisundercontinuingstudy.Diffractioneffectsusuallycausetheapparentareaofaspecimentobegreaterthanitsgeometricalarea,therebyincreasingthecoefficientsmeasuredaccordingtothistestmethod.Whenthetestspecimenishighlyabsorptive,thesevaluesmayexceedunity.Thecoefficientsmeasuredbythistestmethodshouldbeusedwithcautionbecausenotonlyaretheareasencounteredinpracticalusageusuallylargerthanthetestspecimen,butalsothesoundfieldisrarelydiffuse.Inthelaboratory,measurementsmustbemadeunderreproducibleconditions,butinpracticalusagetheconditionsthatdeterminetheeffectiveabsorptionareoftenunpredictable.Regardlessofthedifferencesandthenecessityforjudgment,coefficientsmeasuredbythistestmethodhavebeenusedsuccessfullybyarchitectsandconsultantsintheacousticaldesignofarchitecturalspaces.FieldMeasurements8212;Whensoundabsorptionmeasurementsaremadeinabuildinginwhichthesizeandshapeoftheroomarenotundertheoperator''scontrol,theapproximationtoadiffusesoundfieldisnotlikelytobeveryclose.Thismattershouldbeconsideredwhenassessingtheaccuracyofmeasurementsmadeunderfieldconditions.(SeeAppendixX2foraprocedurethatcanbeusedinthefieldwithlesssophisticatedinstrumentation.)1.1Thistestmethodcoversthemeasurementofsoundabsorptioninareverberationroombymeasuringdecayrate.Proceduresformeasuringtheabsorptionofaroom,theabsorptionofanobject,suchasanofficescreen,andthesoundabsorptioncoefficientsofaspecimenofsoundabsorptivematerial,suchasacousticalceilingtile,aredescribed.1.2FieldMeasurements8212;Althoughthistestmethodprimarilycoverslaboratorymeasurements,thetestmethoddescribedin4.1canbeusedformakingfieldmeasurementsoftheabsorptionofrooms(seealso5.5).Anon-standardmethodtomeasuretheabsorptionofroomsinthefieldisdescribedinAppendixX2.1.3Thistestmethodincludesinformationonlaboratoryaccreditation(seeAnnexA1),asymmetricalscreens(seeAnnexA2),andreverberationroomqualification(seeAnnexA3).1.4ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.
【中国标准分类号】:P31
【国际标准分类号】:91_120_20
【页数】:11P.;A4
【正文语种】:英语