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CHAPTER2
NOISECONTROLININDUSTRIALHALLS
2.1INTRODUCTION
Theproblemofnoisecontrolinindustrialhallsisparticularlychallenging.Passive
controlisinmanycasesineffectiveorcannotbeapplied.Forinstance,intheball-
bearingpulverizerhallorintheturbo-generatorhallofapowerplant(seeFig.2.1)
thenoisepressurelevelmayexceed110dB,whatsignificantlylimitsstaffworking
timeandmakescommunicationimpossible.Turbo-generatorscannotbeisolated
withsoundabsorbingmaterials,becausetheywouldoverheatthenandbrakeasa
consequence.
Thestaffneedstowalkaroundthepulverizersandturbo-generators,monitor
theirperformanceandmaintainthem.Similarsituationisencounteredinother
halls,includingassemblylines,atashapingmachinery,etc.Currently,passive
personalhearingprotectorsarecommonlyused.However,whenconsultingwith
theworkers,theyexpressveryhighinterestinasolution,whichmightreducethe
noisewithoutnecessityofwearinganypersonaldevices.Globalactivecontrolisin
largehallsabsolutelyunfeasible,extremelyexpensive,andunnecessary.
Generatingtheso-calledlocalzonesofquietaroundworkers’headsisthusof
utmostinterest[Elliott,2001].Itistechnologicallyfeasibleandacceptable.It
requiresreasonableenergyamounttodrivesecondarysourcesandthereforeisalso
economicallyefficient.
