Designation:C634−13´1StandardTerminologyRelatingtoBuildingandEnvironmentalAcoustics1ThisstandardisissuedunderthefixeddesignationC634;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ε1NOTE—EditorialcorrectionsmadethroughoutinOctober2016.INTRODUCTIONInsomeoftheentries,thosethataremeasuresofphysicalquantities,thetermisfollowedbyseveralitems:anabbreviationorasymbol,orboth,thedimensionsofquantities,themeasurementunits,andthepartofspeech.Theabbreviation,whereapplicable,indicatesthetermastypicallyreferenced.Thesymbolstandsforthemagnitudeofthequantityinmathematicalexpressions.Thedimensionsofaquantityexpressitsmeasureintermsofthreefundamentalquantities:Mformass,Lforlength,andTfortime.Speed,forinstance,isthequotientobtainedwhenthedistanceanobjectmovesisdividedbythetimeinvolved.Thedimensionsare[LT−1],thenegativeexponentindicatingdivision.ThemeasurementunitsareconsistentlyinSI,LeSystèmeInternationald’Unités.Thosestillusingthecgs(centimetre-gram-second)ortheinchpoundsystemofunitsarereferredformostoftheconversionfactorstoIEEE/ASTMSI10.SomeconversionfactorsarelistedinSection5ofthisdocumentforconvenientreference.Thedimensionsofaquantityarethesameregardlessoftheunitsinwhichthequantityismeasured.Speedhasthedimensions[LT−1]whetheritismeasuredinmilesperhour,feetpersecond,ormetrespersecond.Quantitieswithdifferentdimensionsarenotthesame.Flowresistanceandspecificflowresistance,forinstance,arequantitiesofdifferentkindseventhoughthenamesaresimilar.Ontheotherhand,quantitieswiththesamedimensionsarenotnecessarilyofthesamekind.Soundenergydensity,forinstance,hasthesamedimensionsassoundpressure,[ML−1T−2],butitisnotakindofsoundpressure.Norisabsorptionwiththedimensions[L2]akindofarea.1.Scope1.1Thisterminologycoverstermsanddefinitionsrelatedtoenvironmentalacoustics.Onlydefinitions...
