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PERCEIVEDNOISELEVEL(PNL)

AscaledevelopedoriginallybyK.D.Kryterin1959toattempttomeasuretheperceivednoisinessofjetaircraftbyobserversontheground.ThescalehasbeenadoptedbytheInternationalStandardsOrganizationforinternationaluse.

AsjetengineswereperceivedtobenoisierthanpropelleraircraftbecauseofdifferencesintheSPECTRUMofthenoisetheyproduce,themethodfollowedasimilarapproachtoLOUDNESSsummationofCOMPLEXTONEs.UsingEQUALLOUDNESSCONTOURS,Kryterconvertedthedecibelscaleintoaseriesofincrements,towhichhegavetheunitoftheNOY.Fromthechartattherightofthegraph,thenoyscalecanbeconvertedintoPNdB.Theequationexpressingthisrelationship(analogoustotherelationbetweenthePHONandSONE)is:

PNdB=40+10log2(noy)

TheDECIBELscaleattheleftofthegraphisforFLATresponse.InconvertingdecibelsontheAWEIGHTINGNETWORKtoPNdB,averyroughmethodistoadd12dBthus100dBA=112PNdB.Thetendencyatpresentisformanyairports'theoretically'toaccept110112PNdBfordaytimeflightsand100PNdBfornightflightsbuttheselimitsaremoregenerallytheoreticalthanactual,andtheyarestillveryhigh.

Seealso:EFFECTIVEPERCEIVEDNOISELEVEL,NOISEANDNUMBERINDEX,NOISEEXPOSUREFORECAST.Compare:COMMUNITYNOISEEQUIVALENTLEVEL,NOISELEVEL,NOISEPOLLUTIONLEVEL,SOUNDLEVEL.

TheexactmethodofcalculatingnoysisanalogoustothatofloudnessindexsummationdescribedunderLOUDNESSandAppendixF.Seealso:LOUDNESSLEVEL.

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Contoursofperceivednoisiness(fromISOrecommendationR507,1966).

Ref.:K.D.Kryter,"TheMeaningandMeasurementofPerceivedNoiseLevel,"NoiseControl6:5,Sept.Oct.,1960,pp.1217K.D.Kryter,"ScalingHumanReactiontoSoundfromAircraft,"JournaloftheAcousticalSocietyofAmerica,vol.31,1959,p.1415I.S.O.RecommendationNo.R507.

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