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EFFECTSOFDIFFERENTCLASSROOMNOISES ONSPEECHPERCEPTION By BUMJUNKIM ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL, OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT OFTHEREQUIREMENTSFORTHEDEGREEOF DOCTOROFPHILOSOPHY UNIVERSITYOFFLORIDA 2004 Copyright2004 by BumjunKim Tomyfamily ACKNOWLEDGMENTS Iwishtoexpressmywhole-heartedappreciationandgratitudetomanypeoplewho supportedinmycompletionofthisdissertation.Iwouldliketothankthechairofmy super\'isorycommittee(ProfessorGaryW.Siebein)forhisencouragement,advice,and support.Iwasgladtohavehimasamentorandarolemodel.Iwouldalsoliketothank mycochair(ProfessorMartinA.Gold)formoralsupportandtrustthroughoutmy doctoralstudy.Forhisguidanceandunlimitedsupportonthisstudy,Ialsowishtothank Dr.CarlCrandell.Inaddition,thisdissertationhasbenefitedimmenselyfromthe constructivecommentsthatIreceivedfrommyothercommitteemembers;Professor BertramY.Kinzey,Jr.;Dr.ChristopherNiezrecki;andDr.JimmieHinze. IowemorethanIcanexpressforthethoughtfulandunconditionalloveofmy fatherandmother.Withoutthem1couldnothavecompletedthisstudy.Ideeplyadmire them.Theloveofmywife,Yoonshin,enabledmetogothroughthislongjourney.My daughter,Minju,cheeredmeandgavemejoyduringthejourney.Igivethankstomy parents-in-lawsforgivingmemywonderfulwifeYoonshinandfortheirsupport, especiallytheirprayersformyfamily.Last,butnotleast,IthankmyGodforallofthe wonderfulpresentshehasgivenmeandforhispresenceduringmyjourneyinthislife. IV TABLEOFCONTENTS Page ACKNOWLEDGMENTS iv LISTOFTABLES vii LISTOFFIGURES viii ABSTRACT xi CHAPTER 1INTRODUCTION 1 2LITERATUREREVIEWANDHYPHOTHESIS 5 SoundSources ..5 SpectralandLoudnessCharacteristicsofVoiceatDifferentVocalEfforts ..6 TemporalCharacteristicsofSpeech ..7 Noise ..9 NoiseMeasurements 13 ReverberationTime 15 Reverberation-TimeMeasurementMethodsandFactors 17 AnalyticalMethods 17 FieldMeasurements 19 FactorsAffectingReverberation-TimeMeasurement 21 SoundScattering(SurfaceScatteringandVolumeScattering) ,21 SurfaceAbsorptionMaterialSpatialDistribution 22 RoomShape 23 Reverberation-TimeMeasurementSuggestedbyInternationalStandard(ISO) ,23 SpeechPerceptionMeasurement ,24 SubjectivePerceptionAssessment 26 Phoneticallybalancedwordscores 26 Rhymetest 26 Modifiedrhymetest(MRT) ,27 Sentencetests ,27 ObjectiveIntelligibilityAssessment ,28 Energyratio-basedspeechintelligibilitymethod ,28 Articulationindex(AI) .30 Speechtransmissionindex(STI) V 43 Rapidspeechtransmissionindex(RASTI) 32 Articulationlossofconsonant(A1cons) 33 EffectsofAcousticVariablesonSpeechPerception 34 OverviewofEffectsofReverberationonSpeechPerception 34 PreviousReverberationStudies 34 OverviewofEffectsofNoiseonSpeechIntelligibility 36 PreviousNoiseStudies 37 Noise-InducedAnnoyance 42 HypothesisandProposedModel 44 3METHOD 46 ResearchDesignOverview 46 SimulationTest 47 NoiseProfiling 50 HumanSubjectTest 53 4MEASUREMENTRESULTS 57 ComputerSimulationStudyResults 57 OverallSimulaitonResults 57 DauerHall342SimulationResultsandAnalysis 58 DauerHall68SimulationResultsandAnalysis 60 FieldMeasurementResult 63 HumanSubjectSpeech-PerceptionStudyResult 91 5CONCLUSIONSANDFUTURESTUDIES 106 APPENDIX A SPEECHPERCEPTIONTESTMATERIAL 11 B CLASSROOMNOISESOURCESANDSPECTRA 11 C STATISTICOFTESTSUBJECTS 136 D NOISESOURCECORRELATIONTEST 137 E CORRELATIONSBETWEENMRTANDNOISESOURCES 139 LISTOFREFERENCES 140 BIOGRAPHICALSKETCH 148 VI LISTOFTABLES Table Page 2-1. Markidesnoiseclassification ..9 22--2. Comparisonofsound-ratingmethod 12 2-3. Frequencyrangesofnoisesourcesandrelatedsoundquality 3- 2-4. Typicalspeechandnoiselevelsinclassroomsfrompreviousstudies ...15 2-5. SabineandFryingRTratiounderdifferentabsorptioncondition ...18 3- 42--6. Summaryofsubjectiveandobjectivespeechperceptionmeasurementmethod....25 7. Articulationindexweightingfactors ..31 2-8. Factorsthataffectannoyance ...42 1. Physicaldimensionofsimulatedrooms ..48 3-2. Globalstatisticofmaterial,source,andRTofsimulatedrooms ..48 3-3. Summaryofbackgroundnoiselevelsusedinthecomputermodelstudies ..50 4. Summaryofnoiseprofilingstudy ..51 1. SpeechTransmissionIndex(STI)variationbyspectrallydifferentnoisesunder differentnoiseloudness(DauerFlail342) ..60 4-2. SpeechTransmissionIndex(STI)variationbyspectrallydifferentnoisesunder differentnoiseloudness(DauerHall68) ..61 4-3. Distancebetw'eensourceandreceiversandsourcelevies ..62 4-4. Speechperceptiontestresultunderdifferentnoiselevelsandspectra ..91 4-5. Comparisonofspeechtests ..93 4-6. Analysisotvarianceforspectralandcontenteffectsonspeechperception ..99 4-7. Analysisotvarianceforspectralandcontenteffectsonannoyance 104 vii A LISTOFFIGURES 2- Figure Page 3- 2-1. Maleandfemalevoicelevelunderdifferentvocalefforts 7 2-2. Variationsinspeechlevelsfoundinpreviousstudies 8 3. Speechperceptionmodel 45 3- 4-1. ComputermodelofDauerFlail68 49 3-2. ComputermodelofDauerHall342 49 3-3. Fourspectrallydifferent45dBAbackgroundnoises 50 3-4. Speechperceptiontestroomarrangement 54 3-5. Annoyancemeasurementform 55 6. Testequipmentfunctionaldiagrams 56 1. SpeechTransmissionInde.x(STl)under4differentnoisespectraand 5diffrentnoiselevels(both DauerHall342and68) 57 4-2. Speech TransmissionIndex(STI)under4Differentnoisespectraand 5differentnoiselevels(DauerHall342) 59 4-3. SpeechTransmissionIndex(STI)under4Differentnoisespectraand 5differentnoiselevels (DauerHall68) 61 4-4. STIcomparisonbetweenDauerHall342andDauerHall68 62 4-5. Noiselevelsatstudentseatingareas 64 4-6. Noisesourcesandloudnessatstudentseatingareas 65 4-7. Noiselevelsmeasuredatsourcelocations 66 4-8. Noisesourcesandloudnessatsourcelocations 66 4-9. Noiselevelsandspectraofair-conditioningsystemnoiseandStudents' talkatstudentseatingareas 67 viii 4-10.Noiselevelsandspectraofdehumidifiers 69 4-11.NoisespectrumofA/Candrunningwaternoiseatsinkmeasuredatstudent seatingareas 70 4-12.Noisespectraandlevelsofwaterrunningnoisefromsinks 71 4-13.Noisespectraofstundents’talk 72 4-14.Noisespectraandnoiselevelofmixednoisesatstudentsseatingareas 73 4-15.OverheadProjector(OHP)noisespectraandlevels 74 4-16.Noisespectraandlevelsfromsupplyregisters 76 4-17.Noisespectraandlevelsfromreturngrills 77 4-18.Summaiyofnoisefromsupplygrillsatstudentsseatingareas 78 4-19.Noisespectraofreturngrillsmeasuredatstudentseatingareas 78 4-20.Noisespectraofceilingfanmeasuredatstudentseatingareas 79 4-21.Noisespectraofrestroomexhaustfans 80 4-22.Computernoisespectra 82 4-23.Noisespectraofcombinednoisesources 83 4-24.Refrigeratornoisespectrumatstudentseatingarea 84 4-25.Noisefromfluorescentlightballastatstudentseatingareas 85 4-26.Wallclocknoiseandfishtanknoiseatsourcelocations 86 4-27.Ambientnoises 87 4-28.Noisespectraofvariousnoisesourcesmeasuredatstudentseatingareas 88 4-29.Noisespectraofvariousnoisesourcesmeasuredatsourcelocations 88 4-30.A-weightednoiselevelsofvariousnoisesources 90 4-31.Speechperceptionsunderdifferentsignal-to-noiseconditions 92 4-32.Speechperceptionunderdifferentnoiselevelsandnoisetypes 94 4-33.Speech-perceptionreductionbydifferentyypesofbackgroundnoiseduring noiselevelchanges 96 IX 0 4-34.Speech-perceptionandstandarddeviation(under45,55,and65dBAnoise levelcondition) 98 44--35.Spectraofnoisesourcesandsoundsourcesat65dBA 100 5- 4-36.Annoyanceunder16differentnoisecondition 103 37.Overallrelationshipbetweenannoyanceandspeechperception 104 1. Speech-perceptionpredictionmodelaccuracybynoisefactors 106 5-2. Speech-perceptionudnerdifferentnoisesourceconditions 11 X