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STAGEACOUSTICSFORSYMPHONY
ORCHESTRASINCONCERTHALLS
SubmittedbyJensJrgenDammerud
forthedegreeof
DoctorofPhilosophy
oftheUniversityofBath
September2009
COPYRIGHT
Attentionisdrawntothefactthatcopyrightofthisthesisrestswithitsauthor.Thiscopyofthe
thesishasbeensuppliedonconditionthatanyonewhoconsultsitisunderstoodtorecognise
thatitscopyrightrestswithitsauthorandnoinformationderivedfromitmaybepublished
withoutthepriorwrittenconsentoftheauthor.
ThisthesismaybemadeavailableforconsultationwithintheUniversitylibraryandmaybe
photocopiedorlenttootherlibrariesforthepurposesofconsultation.
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Acknowledgments
Iwouldliketothankeveryonewhohasgenerouslycontributedtotheworkformingthisthesis:
First of all the musicians of professional symphony orchestras who have taken part in
discussions(inalphabeticalorder):DavidDaly,ChrisGale,GunnarIhlen,KevinMorgan,Finn
Orestad,TorbjrnOttersen,MikeSmith,GeirSolumandBengtArstad. Iwouldalsoliketothankall themusicianswhorespondedtoquestionnaires,thecontactpersonswithinallthe
symphonyorchestraswhokindlycollaboratedinthisprojectandmywifeSiljeMarieSkeiefor
allusefulinputasamusician.
Peoplefromwithinthedisciplinesofacoustics,audioandsciencewhohavesharedtheirown
resultsandgivenvaluableinputtothisresearch(inalphabeticalorder):NielsWernerAdelman-
Larsen,JohanAndersson,PeterDAntonio,SteveBarbar,AlfBerntson,BertievandenBraak,
AndersBuen,EddyBghBrixen,StephenChiles,Bengt-IngeDalenback,AndersChristian
Gade, MariaGiovannini, David Griesinger, Tor Halmrast, Masahiro Ikeda, EckhardKahle,
JohnOKeefe,AsbjrnKrokstad,RussellMason,BobMcCarthy,J urgenMeyer,GeoffMiles,
EckardMommertz,LarsHenrikMorset,FrancisRumsey,AnssiRuusuvuori,MagneSkalevik,
OlavSkutlaberg,AudunStrype,PeterSvensson,KanakoUeno,IanWalkerandmembersof
theSyn-Aud-ConforumandtheAUDITORYlist.
Allfellowplayerswhohavetoleratedthesqueaksfrommyclarinetsandsaxophones,allowing
metogetvaluableexperienceonhowitistoplaywithinacousticensemblesoverthelastfive
years:NordreAkerJanitsjar(Oslo),WindBandandUniversityOrchestra(UniversityofBath)
andBathAllComersOrchestra. Alsoabigthankyoutoall fellowpostgraduates,academic
andsupportstaffattheUniversityofBathandthepeopleatBrekke&Strandakustikk.
IamalsoverythankfultoEckhardKahle,AndyShea,Bengt-IngeDalenback,GunnarIhlen
andMagneSkalevikforprovidingvaluablecommentsonpreliminaryversionsofthethesis.
Lastbutnotleast,IammostgratefultomysupervisorMikeBarronforinvitingmetotakepart
inthisprojectandforgenerouslysharinghisknowledgeandguidingmetowardscompletion
ofthisthesisandmywifeandsonforallsupportandinspiration.
TheresearchprojectonwhichthisthesisisbasedwasfundedbytheEngineeringandPhysical
SciencesResearchCouncil(EPSRC),UK.
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Abstract
The main goals for this studywereto better understand whatare the acousticconditions
physicallywithinasymphonyorchestraonconcerthallstages,howthesephysicalconditions
affecttheplayersandultimatelyhowtodesignvenuessuitableforsymphonyorchestras.This
wasinvestigatedbyuseofseveraldifferentapproaches,includingquestionnairesurveysand
dialoguewithmusicians,scaleandcomputermodellingandmeasurementsofexistingstages.
Theresultsfromtheorchestracollaborationsindicatethatthefollowingareofmostconcern
forplayersregardingacousticconditions: hearingallotherplayers in theorchestraclearly
andhavingsoundfromotherswellbalancedwiththesoundoftheirowninstrumentandthe
acousticresponse fromthemainauditorium. Thesesubjectiveaspectsappearto relate to
complexperceptualeffectsliketheprecedenceeffect,maskingeffectsandthecocktail-party
effect.Whenrelatingtheseeffectstophysicalconditions,anarrowandhighstageenclosure
withthestagehighlyexposedtothemainauditoriumappearsmostbeneficial.
Regarding musicians impressions of actual stages and objective measurement results,
existingmethodsforassessingthestageacousticallybyuseofomnidirectionaltransducers
withouttheorchestrapresentwerefoundtohaveonlylimitedrelevance. Thereliabilityand
validityofthemostcommonacousticmeasures(includingST )werestudiedindetail.
Fortheassessmentanddesignofstageenclosures,newmethodsandobjectivearchitectural
measureshavebeenproposed. Acombinationofacousticandarchitecturalmeasuresare
found to successfully discriminate the most preferred from the least preferred stages of
purpose-builtconcerthalls.Theresultsfromjudgementsofexistingstagessupportthefinding
ofanarrowandhighstageenclosurewithahighlyexposedstagebeingmostbeneficial.Theobjectivemeasuresstudiedaresimplifiedrepresentationsofrealacousticconditions.Howto
improvetheassessmentofacousticconditionsonstageisalsodiscussed.
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Preface
Thisthesisissplitintoninemainchapters:
Chapter1:Introduction.
Chapter2:Backgroundofthestudy.Theliteraturereview.
Chapter3:Musiciansimpressionsofacousticconditions. Studiesofimpressionsofacous
ticconditionsonstageingeneralterms.
Chapter4:Soundpropagationwithinasymphonyorchestra. Studies of how the sym
phonyorchestraitselfaffectsoundpropagationbetweenplayers.
Chapter5:Theeffectofreflectedsoundbacktowardsasymphonyorchestra. Studiesof
howreflectedsoundmayaffectperceivedconditionsamongtheplayers.
Chapter6:Computermodellingofstageenclosuresincludingafullsymphonyorchestra.
Studiesofhowtorepresentasymphonyorchestraincomputermodels.Thedeveloped
representation of an orchestra is used to study resulting acoustic responses under
differentstageenclosuredesigns,withasymphonyorchestrapresentonstage.
Chapter7:Acousticmeasuresforassessingacousticconditionsonstage. Studiesofthe
validityandreliability ofacousticresponsesandmeasures,assessedwithouta sym
phonyorchestrapresentonstage.Valuesoftheacousticmeasuresarecomparedwith
subjectiveimpressionsforasetofexistingstages.
Chapter8:Impressionsofeightperformancespacesvisitedregularly. Studiesofoneor
chestras impressions of acoustic conditions in eight performance spaces they visit
regularly.
Chapter9:Overalldiscussionandconclusions.
Preliminaryresultsfromtheresearchprojectformingthisthesiswerepresentedatinterna
tionalconferencesonacoustics(Barron&Dammerud (2006), Dammerud&Barron(2007)
andDammerud&Barron(2008)).Copiesofthesepapersarenotincludedinthisthesis.
ThisthesiswaspreparedinLATEX(setfordouble-sidedprinting)usingMiKTeXandLEd.
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Contents
1 Introduction 15
2 Backgroundofthestudy 19
2.1 Physicalobjectivesoundbehaviourwithinsymphonyorchestras . . . . . . . . 19
2.2 The impressions of acoustic conditions on stage . . . . . . . . . . . . . . . . . 22
2.2.1 Studies of general impressions . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.2 Studies of impressions of specific stages . . . . . . . . . . . . . . . . . 24
2.2.3 Laboratory experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.3 Proposed acoustic measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.4 Effectofstageenclosureforconductorandaudience. . . . . . . . . . . . . . . 31
2.5 Approaches used for this study . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3 Musiciansimpressionsofacousticconditions 35
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.2 Questionnaire method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.3 Questionnaire results in general . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.4 Open questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.4.1 Non-acoustic issues important on stage . . . . . . . . . . . . . . . . . . 37
3.4.2 Favourite halls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.4.3 Preference for risers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.4.4 Hearing others and oneself . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.4.5 Statementsongoodacousticsforperformers . . . . . . . . . . . . . . . 39
3.4.6 Informationcontainedin,anddirectionofreverberantsound. . . . . . . 40
3.4.7 Bloom and projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
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3.4.8 Discussionandconclusionsofresultsforopenquestions . . . . . . . . 41
3.5 Preference rating questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.5.1 Comments on loud instruments . . . . . . . . . . . . . . . . . . . . . . . 45
3.5.2 Commentsonproblemswithfocusingonparticularinstruments. . . . . 45
3.5.3 Commentsonawarenessofreflectingsurfaces . . . . . . . . . . . . . . 45
3.5.4 Correlation of the rating responses . . . . . . . . . . . . . . . . . . . . . 46
3.5.5 Discussionandconclusionsofpreferenceratingresults . . . . . . . . . 46
3.6 Specific halls rated by the players. . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.6.1 Theeffectofwhichorchestrasjudgingacousticconditions . . . . . . . . 49
3.6.2 Objectivemeasuresassociatedwiththepurpose-builtconcerthalls . . 50
3.6.3 Relationshipsbetweenaverageoverallacousticimpressionand objective measures . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.6.4 Comparisonofhighandmediumscoringhalls . . . . . . . . . . . . . . 54
3.6.5 Discussionandconclusionsofresultsforspecifichalls . . . . . . . . . . 55
3.7 Overall conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4 Soundpropagationwithinasymphonyorchestra 59
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.2 Analyticalinvestigationsofsoundlevelsonstagewithoutorchestrapresent . . 60
4.3 Experimentalinvestigationsofsoundlevelsonstagewithorchestrapresent . . 62
4.3.1 Scalemodellingsystemandconfiguration . . . . . . . . . . . . . . . . . 63
4.3.2 Measurement analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.3.3 Measurement conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.3.4 Resultsanddiscussionfororchestraonflatstagefloor. . . . . . . . . . 67
4.3.4.1 Along path A . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.3.4.2 Along paths B and C . . . . . . . . . . . . . . . . . . . . . . . 68
4.3.4.3 Theeffectofreflectionswithintheorchestra . . . . . . . . . . 69
4.3.4.4 The influence of source directivity . . . . . . . . . . . . . . . . 70
4.3.5 Resultsanddiscussionfororchestraonrisers. . . . . . . . . . . . . . . 71
4.3.5.1 Along path B and C . . . . . . . . . . . . . . . . . . . . . . . . 71
4.3.6 Linearmodelsoftheorchestraattenuation . . . . . . . . . . . . . . . . 72
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6.3 Validation of within-orchestra sound levels . . . . . . . . . . . . . . . . . . . . . 106
6.3.1 Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.4 Validation of early part impulse responses . . . . . . . . . . . . . . . . . . . . . 108
6.4.1 Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6.5 Comparison of overhead and side reflections . . . . . . . . . . . . . . . . . . . 110
6.5.1 Results for sound level across the stage . . . . . . . . . . . . . . . . . . 113
6.5.2 Results for impulse responses . . . . . . . . . . . . . . . . . . . . . . . 114
6.5.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
6.6 Comparisonofsixdifferentstageenclosuredesigns . . . . . . . . . . . . . . . 116
6.6.1 Resultingimpulseresponses,violintodoublebass . . . . . . . . . . . . 119
6.6.2 Resultingimpulseresponses,trumpettodoublebass . . . . . . . . . . 120
6.6.3 Resultingimpulseresponseswithoutorchestra,violintodoublebass. . 122
6.6.4 Results for acoustic measures . . . . . . . . . . . . . . . . . . . . . . . 123
6.6.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
6.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
7 Acousticmeasuresforassessingacousticconditionsonstage 127
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.2 Effects of an orchestra on stage measurements . . . . . . . . . . . . . . . . . . 128
7.2.1 Changes of impulse responses . . . . . . . . . . . . . . . . . . . . . . . 128
7.2.2 Resultsanddiscussionformeasuredimpulseresponses . . . . . . . . 129
7.2.3 Changes of acoustic measures . . . . . . . . . . . . . . . . . . . . . . . 130
7.2.4 Resultsanddiscussionforacousticmeasures . . . . . . . . . . . . . . 131
7.2.5 The effect of chairs on stage . . . . . . . . . . . . . . . . . . . . . . . . 134
7.3 Acoustic measures collected from eight stages . . . . . . . . . . . . . . . . . . 134
7.4 Spatialaveragevalueofacousticmeasuresassessedwithoutorchestra . . . . 136
7.4.1 Variationsoftheveryearlypartoftheimpulseresponse . . . . . . . . . 137
7.4.2 Variations of acoustic measures . . . . . . . . . . . . . . . . . . . . . . 138
7.4.3 Discussion and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 138
7.5 Results for objective acoustic measures . . . . . . . . . . . . . . . . . . . . . . 139
7.5.1 Stage measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
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7.5.2 Correlationbetweentheacousticmeasuresassessedonstage . . . . . 140
7.5.3 Audience area measurements . . . . . . . . . . . . . . . . . . . . . . . 141
7.6 Relationshipsbetweenstageandaudienceaveragevalues . . . . . . . . . . . 142
7.7 Reliability of the Support measures. . . . . . . . . . . . . . . . . . . . . . . . . 143
7.8 Monophonicomnidirectionalmeasuresforassessingacousticconditionswithout orchestra present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
7.9 Directionallydependentassessmentofstageacousticresponse . . . . . . . . 147
7.10 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
8 Impressionsofeightperformancespacesvisitedregularly 151
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
8.2 Method for subjective investigations . . . . . . . . . . . . . . . . . . . . . . . . 153
8.3 Methods for objective investigations . . . . . . . . . . . . . . . . . . . . . . . . 154
8.3.1 Acoustic measures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
8.3.2 Architectural measures . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
8.4 Questionnaire results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
8.4.1 Commentsfromtheplayersandmeetingwithplayers . . . . . . . . . . 157
8.5 Relationshipsbetweensubjectivecharacteristics . . . . . . . . . . . . . . . . . 158
8.5.1 Subjectivecharacteristicsrelatedtooverallacousticimpression. . . . . 158
8.5.2 Differencesofsubjectivecharacteristicsbetweentheeightvenuesand instrument groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
8.6 Results for objective acoustic measures . . . . . . . . . . . . . . . . . . . . . . 160
8.6.1 Relationshipsbetweentheacousticandarchitecturalmeasures. . . . . 161
8.6.2 The importance of hall reverberation . . . . . . . . . . . . . . . . . . . . 161
8.7 Relationshipsbetweensubjectiveandobjectivemeasures . . . . . . . . . . . . 163
8.7.1 Results of correlation analysis . . . . . . . . . . . . . . . . . . . . . . . 164
8.7.2 The relevance of acoustic measures . . . . . . . . . . . . . . . . . . . . 164
8.7.3 The relevance of architectural measures. . . . . . . . . . . . . . . . . . 166
8.8 Architecturaldetailsrelatingtoacousticimpressions . . . . . . . . . . . . . . . 167
8.9 Combinedstudyincludingresultsfromcomparablestudies . . . . . . . . . . . 167
8.10 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
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9 Overalldiscussionandconclusions 173
9.1 Themusiciansimpressionsofacousticconditions . . . . . . . . . . . . . . . . 174
9.2 Acousticconditionsimposedbythearrangementofasymphonyorchestra. . . 175
9.3 Requirementsofauditoriaforsuitablestageconditions
for symphony orchestras. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
9.4 Stageenclosuredesignssuitableforsymphonyorchestras . . . . . . . . . . . 177
9.5 Relevanceofmeasuredomnidirectionalacousticresponsesforassessingthe stage enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
9.6 Overall outcomes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
9.7 Future work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
References 181
A Thesymphonyorchestra 189
A.1 Orchestra arrangements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
A.2 Directionalcharacteristicsoforchestrainstruments . . . . . . . . . . . . . . . . 190
A.3 Stage floor area per musician . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
A.4 Stage risers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
B Questionnaires 193
C Frequencyresponseofpanelreflections 199
D Combfiltering 203
E Thelateralfractionmeasureappliedtotwostageenclosures 205
F Strypesreversedorchestraarrangement 207
G ImprovedacousticconditionsontwoNorwegianstages 209
G.1 Oslo Concert Hall, Oslo (OCH) . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
G.2 Olavshallen, Trondheim (TOH) . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
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Chapter1
Introduction
This study and studies by others (Gade (1989b), Meyer (2009), Naylor (1988), Ueno &Tachibana(2003))revealthatacousticconditionsonstageareveryimportantforsymphony
orchestramusicians. Forsymphonyorchestras,theacousticconditionswithin theensemble
itselfaredifferentfromsmallerensembleslikechamberensembles. Thesizeofasymphony
orchestra leads to the sound from most distant fellow players being significantly delayed
andattenuated. Concerthallshavehistoricallybeenpurpose-builtforsymphonyorchestras,
withthesizeofthestageandauditoriumtoaccommodatetheorchestraandtheorchestral
repertoire. Butevenamongsuchpurpose-builthalls, therearestageswhicharelikedand
thosethataredislikedbyperformers. Theoverallgoalsforthisprojectwereto learnmore
abouthowacousticconditionsaffecttheplayers,andhowthedesignofthestageenclosure
and auditorium affects the acousticconditions for the players. These investigations were
carriedout independentofanyhypotheses. Morespecificallytheoverallgoalscanbesplit
up into three: gaining understandingof themusicians impressions ofacousticconditions,
recognisetypesofvenueandthirdlyestablishingwhichstageenclosure(stageshell)designs
provide good acousticconditions for the players. Objective measures, both acousticand
architectural,havebeenstudiedtosearchforhowgoodacousticconditionsmaybedescribed
ordetectedphysically.Thesegoalsareatatoplevelofrelationsbetweenacousticconditions
and the performers. This means that the focus for this workhasbeen to find the major
relations. The underlying mechanisms for the major relations are only partly studied in
detail. Amajoroutcomeof thisstudywould be tobetter understandhow todesign halls
andstageenclosuresthatwillprovidegoodacousticconditionsforsymphonyorchestras,who
consequentlywillperformbetter.
Historically the focus inauditorium acoustics has been on the acousticconditions for the
audience.Eventhoughacousticconditionsfortheperformerscertainlyhavebeendiscussed
vividlyamongtheperformersthemselvesforcenturies,theseaspectsofconcerthallacoustics
donotappeartohavebeengivenpriorityamongacousticians(investigatingthescienceof
acoustics). Theremightbeseveralreasonsforsuchaweaklinkbetweenphysicalacoustic
conditionsandperceivedconditions,butoneofthemainreasonscouldberelatedtotherole
physicalconditionshaveforageneralperformer.Musicianshavelearntoveryearsoftraining
andexperiencehowtocopewithdifferentacousticconditions. Theyappeartorelateto the
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acousticconditionsonamoresub-consciouslevelofperception.Iftheyconsidertheacoustic
conditionsindetailwhileplaying,they risklosingfocuson themusicalperformance. Such
mechanismsbehind musicalperformancehavebeendescribedby for instanceKlaveness
(2008). Whenacousticiansask themusiciansaboutacousticconditionsandpreferencefor
certainstageconditions,themusiciansare(forgoodreasons)likelytonothavemanyanswers
whichwillbeinformativefortheacousticians.
The aboveobservations suggest that itwillbeverychallenging for the musicians tohave
wellfoundedobservationsofhowforinstancethearchitecturaldesignsofthevenueaffect
them. Someplayersmayhaveideasofhowdifferentacousticconditionsaffectthem,butas
discussedbyBarron(1993)wecannotexpectanobserver(musician)tounravelacomplex
situationjustfromsimpleexperience. Theprioritiesofattentionandeducationalbackground
asaperformercanalsocontributetochallengesbeingabletocommunicatesuchdiscoveries
clearly/efficiently to for instance acousticians. The musicians are not trained within any
physicalsciencedisciplines,andacousticiansoftenhavenoformaleducationorexperience
inmusicandperformance.Thereisahighriskofanydiscoveredrelationscanbelost,simplybecause the two groups have a different vocabulary, or the reason mightbe that the two
partsrarelycommunicateatallwithregardtoperceivedacousticconditions. Gade(1981)
interviewedmusiciansabouttheirimpressionsandrelationstoacousticconditionsonstages.
One ofhis findingswas that the musicians very rarely discussed acousticconditionswith
acousticians. Unfortunately, this workhas neverbeen published inany scientific journal.
Blauert (2007)hasraisedconcernaboutthemismatchoffocusbetweenacousticiansand
usersofacousticspaces,andthatthismismatchcanleadtoproblemswhenthesetwogroups
trytocommunicate(exchangeideas/views).
Howcouldstudiesaiming to raise theunderstandingofacousticconditionsforperformers
overcome these problems sufficiently? In other disciplines like audio technology and
psychoacoustics,itiscommontosimulatedifferentacousticenvironments/conditionswhereit
ispossibletoquicklyswitchbetweendifferentconfigurations. Systemshavepreviouslybeen
implementedtosimulateacousticconditionsforsoloisticplayingandfortwomusiciansplaying
together,withandwithoutvisualcommunication(Naylor&Craik(1988),Gade(1989b),Ueno
&Tachibana(2003)andGuthrie(2008)). Inrealconditions,thecommunicationbetweentwo
playersisaffectedbythesoundfromtherestoftheorchestraplaying.Withoutincludingthe
completeorchestrathevalidityofsuchlaboratoryexperimentsislikelytobelimited, though
certainaspectsofacousticconditionsmaybe studied. Hallswithflexiblestageenclosuresofferexcitingpossibilities forresearch,butsuchhallsareunfortunatelyrare. Mostexisting
concerthallshavefixedarchitecturaldesigns,whereonlyminorchangesarepossible(only
afewhallsexistgloballywherethestageenclosureishighlyconfigurable). Withfixedstage
enclosuredesigns,differenthallsneedtobestudied. Thenumberoforchestrasinvolvedand
howmanytimestheorchestra(s)haveplayedineachhallarefactorslikelytoaffectthevalidity
ofsuchstudies.Therewillthereforebesignificantshortcomingsforbothapproacheseither
reducednaturalnessandnotincludingafullorchestrainlaboratoryexperiment,orareduced
controlandflexibilityoftheacousticconditionsinstudiesofrealhalls.
Giventhesechallenges,acombinationofdifferentapproacheshasbeenusedforthisstudy.
Thetwomajortypesofapproachesmaybedescribedassubjectiveandobjectiveapproaches.
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Thesubjectiveapproachincludesinvestigationsofimpressionsofacousticconditionsamong
orchestralplayersingeneralandrelatingtospecificexistingstages. Theobjectiveapproach
includesstudiesofphysicalconditionsinthevenuesthatwerejudgedbytheplayers,butalso
howthearrangementofasymphonyorchestraimposescertainacousticconditionsforthe
players(throughscalemodelling)andinwhatwayconditionsmaybeimprovedbyastage
enclosure. Theresultsfromthesetwodifferentapproacheswerecomparedtoeachotherto
guidethefocusfortheinvestigationsthrough-outtheproject,andtosearchforvalidrelations
betweenphysicalacousticconditionsandsubjectiveimpressions.Hypotheseswithregardto
howacousticconditionsareperceivedamongplayershavealsobeendevelopedthroughthe
authorsownexperienceasanamateurmusicianwithin largerensembles. Thiswouldbeon
alessscientificlevel(sinceamateurandprofessionalsmayjudgeacousticconditionsvery
differently),buthasbeenveryusefulforanacoustician(theauthor)tobetterunderstandthe
playerspointofview.
Thestudyofgeneralimpressionsamongtheplayersincludewhatperceptualaspectsthey
findimportantforgoodstageacousticconditions,problemstheymostfrequentlyface,theirfavouritehallvisitedthrough-outtheircareeretc. Suchimpressionswillbebasedonseveral
years of experience. Eight different professional orchestras within England and Norway
participatedinaquestionnairesurveycoveringsuchgeneralimpressions. Forthesubjective
studiesofexistingstages,therehasbeenaimedforhighnumbersofstages/hallsandplayers
participating in the study. Focus has been on impressions among players visiting a set
ofhalls frequently (excludinghome venues), for reducing the influenceof factors varying
betweenperformances(likerepertoire)andallowingtheplayerstohaveestablishedthemost
valid impressions. Impressionofexistingstageswere investigatedintwodifferentstudies:
impressions of overall acoustic impression for the halls visited regularly by seven of the
eightorchestrasmentionedabove,aswellasadetailedstudywithoneoftheprofessional
Englishorchestras. Forthehallsvisitedby theeightorchestrasbasicobjectivedatawere
collected, both acousticand physical dimensions related to the stageenclosure. For the
detailedstudy,theorchestraplaysregularlyinasetofeighthalls,aboutwhichmostofthe
playershavedevelopedtheirviewsoverseveralyears. Theirimpressionswereinvestigated
throughquestionnairesdistributed to the playersand through interviews with someof the
players. Objectivedatawerecollectedalsoin thisstudy,buttheacousticconditionsinthe
eighthallswereinvestigatedindetailbymeasuringmonophonicroomimpulseresponseson
thestagesandwithintheaudiencearea. Asasummary,thisstudyincludesjudgementsof
totally20purpose-builtconcerthallswhichtheplayersvisitregularly.
The objective studies included theoretical/analytical investigations, scale modelling and
computermodelling. Scalemodelswereusedtostudytheacousticconditionssetupbythe
orchestraitself,inparticularhowthescreeningeffectscausedbyplayersandobjectsonstage
affectsoundpropagationbetweenplayers. Scalemodelswerealsousedto investigatethe
possibleconsequencesofmeasuringacousticconditionsonstagewithoutafullsymphony
orchestra present. How such initial acousticconditions set upby the orchestra couldbe
improvedby the introduction ofa stageenclosure, isstudiedanalyticallywithreference to
availableliteratureonperceptualeffectsthatappearmostrelevantfortheplayers.Computer
modelling was used tostudyacoustic conditionsonstagewitha full symphonyorchestra
present,andhowtheconditionsareaffectedbydifferentenclosureelementsanddesigns.
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Thisthesisisstructuredindifferentcompletechapterscoveringdifferenttopics. Chapter2
contains the literaturereviewformingthebackgroundof thestudy. Thesubjectivestudies
aredescribedinChapters3and8,whiletheobjectivestudiesaredescribedinChapters47.
Chapter3describestheresultsfromquestionnairesdistributedtotheeightdifferentorchestras
within England and Norway. Chapter4 investigates the sound levelswithin the orchestra
itself,andhowthe screeningeffectscausedbyplayersandobjectsonstageaffectsound
propagation between players. Chapter 5 investigates extreme types of stage enclosure
designsbysimplifiedanalyticalmethods,whereresultingdifferencesarecomparedtofindings
related toperception ofsound ingeneral and findingsby others with regard toenclosure
designs.Chapter6considerscomputermodellingofgenericstageenclosuredesignstogeta
morecompleteimpressionofhowthedifferentdesignsaffectacousticconditions. Chapter7
coversacousticmeasuresrelatedtoexistingstage,whileChapter8 includesthesubjective
resultsintheeightdifferenthallsvisitedregularlybyoneorchestrawithreferencetoobjective
results.
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Chapter2
Backgroundofthestudy
Thisreviewoftheliteratureonstageacousticsforsymphonyorchestrasinconcerthallsissplitintofourmajorsections. Thefirstsectiondiscussesphysicalacousticconditionswithin
theorchestra.Thesecondsectioncoverssubjectiveimpressionsformusiciansonstage.The
twofinalsectionscoverobjectivemeasuresproposedforevaluatingacousticconditionsforthe
performersandhowdesignofthestageenclosureaffectsconditionsfortheconductorandthe
audience.Thesefoursectionscoverthebasicconcernsofthisproject.Themethodsusedfor
thisstudyarediscussedinthelastsectionofthischapter.
2.1 Physicalobjectivesoundbehaviourwithinsymphonyorchestras
Sincearound1950,alotofresearchworkhasbeendevotedtoacousticconditionsforthe
audiencein concerthalls. Thisworkis discussedand summarised by Barron (1993)and
Beranek(2004),forinstance. Oneoutcomeofthisresearchisasetofobjectivemeasures
relatingtoconditionsforlistenersbeingincludedinthestandardISO3382(ISO,1997).Study
ofconditionsformusiciansonconcerthallstageshasontheotherhandreceivedmuchless
attention.Whathasbecomeclearisthattheacousticrequirementsoflistenersandperformers
overlapregardingqualityof thesound(likewarmth, tonecolour),butperformersalsoneed
toheartheirowninstrumentandbeingable tocommunicatewiththeircolleagues through
thesoundstheyproduce. Whetheranyof themeasuresusedforconcerthall listeningare
likelytobesuitableforacousticconditionsforperformersisdebatable.Thisquestionisfurther
exploredinSection2.2.
Asignificantdifferencebetweenconditionsforaudienceandplayersistherangeofsource-
receiverdistances. Foranaudiencemember10mfromthestagefront,thedistancetothe
closestand farthestmusician will typically bein a ratioof 1:2 (a6dBdifferenceof direct
soundlevels). Mostlistenersarefurtherawayfromthestageandtherangeofdistancestoallinstrumentswillbesmall. Foraperformerinanorchestra,someplayerswillbecloseby,
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whileotherplayerscanbeupto20mawayfromeachother(fora16mwideand12mdeep
stage). Thedistancesinvolvedwilldependonhowtheplayersarearrangedonstage(see
AppendixAformoredetails).Thisleadstoadistanceratiooftypicallyupto1:20betweenthe
distancetotheclosestandmostdistantplayer.Sucharatiocorrespondstoa26dBdifference
ofdirectsoundlevels averysignificantdifference. Additionally, thesoundpathbetween
distantplayerswillbeobscuredbyotherplayerssittinginbetween,aswellasmusicstands
andinstruments. Soundreflectionsinternallywithintheorchestrawillcompensateslightlyfor
thisattenuationbyotherplayersetc.
Howtheorchestraitselfcontributestotheattenuationofthedirectsoundwithintheorchestra
isobviouslyimportantforon-stageconditions.Thishaspreviouslynotbeenstudiedindetail.
SomebriefstudieshavebeencarriedoutbyKrokstadet al.(1980),Ikedaet al.(2002)and
Skalevik(2007). Krokstadet al.(1980)studiedsoundpropagatingthroughagroupofnine
personssitting onaflat floor, while Ikedaet al. (2002) studied sound levelswithin a real
symphonyorchestraatsource-receiverdistances26m. Skalevik(2007)studiedthesound
levelswithin050ms(relativetothearrivalofthedirectsound)withdifferentsourceheightsatonesource-receiverdistanceof12m. Mommertz(1993)hasstudiedsoundpropagation
throughrowsofaudiencesittinginatheatre,presentingresultsintermsofattenuationper
metre.TheresultsfromMommertzsstudycannotbeapplieddirectlytotheconditionswithin
theorchestra,sincethedensityofpeopleisdifferentforanorchestraandmusiciansarenot
arrangedinrows. Thistopic ispursued furtherinSection4.3.7. Thesestudiesgivesome
indicationsoftheobstructioneffectbytheorchestra,withoutanywellfoundedquantification
oftheattenuationtoexpectalongdifferentpathswithintheorchestrawiththewholerangeof
relevantsource-receiverdistances.Thestudiesabovegivesomeindicationoftheobstruction
effectsoforchestraplayers,buttheresultsarefarfromcomprehensive.
Thesoundlevelofmusicalinstrumentswithinanorchestrainparticulardirectionsisdescribed
bytheirdirectivities.Thedirectivityofmusicalinstrumentsforasymphonyorchestrahavebeen
measuredbyOlson(1967)andmoreextensivelybyMeyer(2009).SeeAppendixAformore
detailsondirectivitiesofaviolinandatrumpet. Theseresultsprovidesomeindicationofthe
directions inwhichmostsoundis radiated. Acomplicating factorwith regard todirectivity
is that the directivity changes depending on the note being played, particularly for string
instruments. According toOtondo & Rindel (2004) the directivityof brass instruments is
reasonablyconsistentbetweeneachnoteplayed.Significantchangesofdirectivitydepending
on the note being played makes it difficult to use measured directivity patterns of stringinstrumentsincalculationsofsoundlevelswithintheorchestra,whiledirectivitypatternsof
brassinstrumentsappearsufficientlyconsistentforestimatingsoundlevels.Musicstandsand
screensbetweenplayerswillalsoaffectthedirectsoundlevelsindifferentdirectionsfromthe
player,particularlyathigherfrequenciesduetolimitedsizeofmusicstandsandscreens.
Meyer (2004)alsostudiedthesourcesoundpoweroforchestralinstruments. Thehighest
power levelswere found for percussion and brass instruments. Normally the percussion
and brass instruments sit at the backof the stagepointing their instruments towards the
audience/conductor. A major consequence of source levels, directivity of the different
instrumentsandhowtheorchestraisarrangedonstage,isthatthedirectsoundlevelsfrom
thedifferentinstrumentsvaryconsiderablywithintheorchestra.
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Proximity tosome instrumentscan lead toexcesssound levelsfornearbyplayers, witha
potentialriskofhearingimpairment.Physicalsoundlevelswithinansymphonyorchestrainan
orchestrapitandtheriskofhearinglossamongorchestralmusicianshavebeeninvestigated
byforinstancePeterset al.(2005),Janssonet al.(1986)andK ariet al.(2001). Leeet al.ah
(2005)carriedoutsimilarinvestigationsformusiciansinorchestrapits.Resultsby K ariet al.ah
(2001)showedthatmanywindinstruments,includingtrombone,flute,piccoloflute,French
hornandclarinetarecapableofproducingsoundpressurelevelsexceeding100dBA.The
resultsforriskofhearingimpairmentvary,with theexposuretoothersoundeventsoutside
themusiciansprofessionallifebeingoneoftheuncertaintyfactors. Suggestedmethodsto
reduceexposuretoexcessivesound levelsinclude theplayersusingearplugsandplacing
soundbarriersbetweenplayers.
Withregardtolowfrequencysoundlevelsandvibrations,Lee(1982)studiedanalyticallyhow
reflectingsurfacesclosetodoublebassesaffectedtotalsoundlevelfromtheseinstruments,
and found that thefloorandsidewallscancontribute toa raised levelat low frequencies.
Askenfelt(1986)foundthroughmeasurementsonrealstagesthatthestagefloorandriserscouldcontribute toperceptually raise the level ofdouble bass. Moredetails are given in
Section5.7.
Bradley (1996)studiedhowaddingastageenclosure(shell)affectedtheobjectiveacoustic
conditionsonstage(aswellasfortheaudience).Twoofthethreeshellsstudiedfullyenclosed
thestage,whileonehadthemainreflectingsurfacesverticallyatthesides. Hefoundthat
addingastageenclosure(shell)aroundtheorchestracontributetoraisethesoundlevelson
stagebytypicallyabout3dB.Soundlevelsofearlysound(directsoundandearlyreflections)
increased by less than3dB,while the levelsof late soundincreasedby 4dB.From this,
Bradleyconcludedthat temporalclarity,asassessedby forinstancetheobjectivemeasure
C80,didnot increasebyaddingashell. Thiscouldbeaffectedbythetypeofshellsused.
Measuredreverberationtime,T ,onstageincreasedatlowerfrequencieswhenstageshells
wereadded.
Thephysicalseparationofplayersofupto20mleadstomaximumdelaysof60msdelay
forthedirectsoundifall theplayersstarttheirnoteatthesameabsolutetime. Timingisof
greatconcernforperformers,becauseit isamongtheaspectofperformanceleastaffected
bytheroomacousticresponse,accordingto Sundberg (2008). Goodman (2003)includes
contributionsfrommusicianswithregardtodifferentaspectsofmusicalperformance,among
themTheillusionofsynchronybyE.Goodman.AccordingtoGoodmantheplayersneedto
takeintoaccountthesynchronicityofsoundasheardbytheaudience. Playersat theback
ofthestagenormallyneedtocompensatefortheirsoundbeingphysicallydelayedrelative
totheplayersatthefrontpartofthestage. Playerssittingacrossthestagemuststarttheir
noteatthesametime,otherwisethesoundwillnotarrivesynchronisedfortheaudience.This
leadstoplayersatoppositesidesofthestagehavingtoignorethedelayofsoundintroduced
byphysicalseparation; visualcommunicationis importantbetweenmanyplayerssincethe
auralcuescanbemisleading. Iftheytry towaitforeachother, theorchestrarisksslowing
downthetempo,asdescribedbyIhlen(2008). (ThisisfurtherdescribedinSection5.4.1.)
Fredrickson(1994)foundthatvisualcuesinadditiontoauralcuesraisedtheaccuracyratings
oftheperformedmusic.Theaccuracyofonsetofnotesisalsofinite.Rasch(1979)foundthat
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triosplayingtogetherhadadeviationoftheironsetofnotesof3050ms. Thisindicatesthat
atimespanof60ms(thedelayofstringsoundacrossthestagetowardstheback)forsound
fromdifferentinstrumentsmaybeseenaspartoftheorchestrasounditself,andtheplayers
treatsuchdelaysastolerabledeviations.
From the investigations regarding physical conditions asdescribed above, thereare only
limited studies regarding quantification ofhow playersand objects on stagecontribute to
obstructsoundbetweentheplayers. Soundlevelswithin theorchestrahaveprimarilybeen
measuredwithregardtoexcesssoundlevels.Regardingcontributionofreflectedsoundfrom
thestageenclosure,onlychangesofaveragestagevalueshavebeenstudied. Nodetailed
studieshavebeenfoundwithregardtothelevelofreflectedsoundfromthedifferentinstrument
groupsprovidedbythedifferentsurfacesofastageenclosure.
2.2 Theimpressionsofacousticconditionsonstage
Someofthemajormechanismsstudiedbyotherswithregardtohowtheacousticconditions
affectthemusiciansinclude: mutualhearingandcommunicationbetweenplayers(including
theratioofsoundlevelandtimearrivalofonesowninstrumentandotherinstruments),and
theinfluenceofreflectedsound(fromthestageenclosureortheconcerthallasawhole).The
latterislikelytoaffectmutualhearingaswell,butthestudiesfocusingonmutualhearinghave
normallystudiedgeneralsoundleveldifferences,whilestudiesonreflectedsoundhaveoften
lookedatspecificreflectingsurfaces.Forthemusicians,thesoundlevelsofotherinstruments
withintheorchestrawillbeheardinrelationtolevelofproducedsoundbytheirowninstrument.
This leads tothe existenceofa maskingsound(ownsound) which isnot present for the
audiencelistener.Thismakesitdifficulttoapplyfindingsregardingmaskingthresholdsbased
onnormallisteningconditions.
Meyer(1994)definedthreedifferentqualitylevelsofacousticconditionsforthemusicians:
The lowest level is associated with the need for playing correctly. If players hear
themselves too loudlyandtheotherparts tooweakly, therhythmicprecisionsuffers.
Inthereversecasetheintonationisaffected,whereasprecisionintimingstillispossible.
The second level relates to forming the sound quality. Ease of singing or a good
responseof their instrument support the musicians security, enhance the accuracy
of toneonsets and articulation, enlarges the dynamic rangeand avoids a too much
enforcedtoneproduction. Easeofhearingeachotherenablesthemusicians toplay
withawell-balanceddynamicrelationtotheotherpart.
Thethirdlevelisassociatedwithcreatinganintegratedentiresoundoftheorchestra,
related tocommonlyproducedarticulationofchordsandcommonlyformed temporal
finestructureofdynamics. Inparticularstringplayersneedasenseofbeing integrated
intotheirgroups.
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Studiesonhowtheacousticconditionsaffecttheplayingconditionscanbesplitupinthree
differentmajorapproaches:studiesofgeneralexperiences,impressionsofspecificconditions
inasetofexistinghalls,andlaboratoryexperiments.Forallthreeapproaches,questionnaires
and interviewshavebeen the major investigative techniques. This section issplit upinto
resultsfromthesethreedifferentapproaches.
2.2.1 Studiesofgeneralimpressions
Gade(1981)interviewed32musiciansaboutdifferentaspectsofacousticconditionsingeneral
andtheirrelativeimportance. Themostimportantaspectsfortheplayers(in rankedorder)
cameoutas:hearingeachother,reverberation,support,timbre,dynamics,timedelay,
change ofpitch. Soloists favoured the aspects that the players felt influencethe beauty
ofthesound,believedtobecontrolledbyreverberation, support, timbreand dynamics.
Accordingtothemusicians,merepersonaldifferencesinjudgementonacousticqualityare
rare (they try toworkasone unit, putting personal tasteaside), but differences between
instrumentswereobserved. Forinstance,playersofpianoand timpani/percussionappeared
tohavedifferentopinionsthantherestoftheorchestra. Musiciansreportedtheyseldomtalk
aboutacousticswithacousticiansorothers.
Gentaet al. (2007b)distributedquestionnairestothemusiciansoftwoprofessionalorchestras,
enquiringwhichacoustically relatedaspects/attributesweremost important forthem. The
resultsindicatedthatensembleandclaritywerethemostimportantattributes,followedby
dynamics, timbre, tonalbalance, soundstrengthand soundenvelopment. TheBorda
countmethodwasfoundasthemosteffectivemethodforfindingtherankorderofthedifferentattributesamongtheplayers. Miller(1987)conductedasimilarquestionnairestudywithone
symphonyorchestrawhere the results indicated that themusicians relations to acoustics
couldbereducedtofourfactors:ensemble,interference,supportandtonequality.Guthrie
(2008),involvingninemusiciansparticipating,foundthefollowingaspectstobehighlyrelevant,
regardingacousticresponse: ratioof volumebetweenyourselfandothers,commonaural
spacebetween all musicians, reverberance of space and ability to distinguish between
individualvoices.Theresultsfromthesethreestudiesagreereasonablywellwiththefindings
byGade(1981).
Meyer (1994)askedmorespecificallydoublebassplayersfor theiropinions onstagefloor
propertiesinaquestionnaire.Theresultsshowedthat50%oftheplayerspreferredawooden
flooroveracavity(moreresonance,morecarryingsound)while50%preferredanon-
vibratingfloor(Thesoundismoreeasilycontrolled,Acavitymakesthesounddull). The
positiveimpressionswerebelievedtoberelatedtoraisedsoundlevelatlowerfrequencies,as
foundbyAskenfelt(1986),whilethenegativeimpressionswereassignedtotheenergyloss
causedbytheenergytransmissionintothefloor.
Ueno&Tachibana(2005)establishedacognitivemodelofmusiciansperceptioninconcert
hallsbasedonan interviewsurvey. Theirmodeldescribeshowthemusiciansrelatetothe
physicalbehaviour ofan acousticspaceas tacit knowinga skillacquiredovertimeby
repeatingthetask,withoutnecessarilybeingabletotellhowtheskillisacquiredandhow
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the physical conditions actually are perceived. The preference or evaluation of acoustic
conditions are found to be affected by the arrangement with other players (solo playing,
quartet,orchestra)andthewordsusedtoexpresstheirexperienceswillvary. Butbytaking
thebackgroundandtheintentionsoftheplayersintoaccountandconsideringthesemantic
aspectsofwordsused,theybelievedthedifferencesofthejudgementscanbeinterpreted.
Overall these results suggest that the musicians relate to the physical conditions at a
subconsciouslevelandthattheabilitytocommunicateclearly/efficientlyisofhighestconcern
amongtheplayers.
2.2.2 Studiesofimpressionsofspecificstages
Withregard tostudiesofperceivedacousticconditionsonspecific(existing)stages, there
arefewstudies involvingafull symphonyorchestra. Investigationsofacousticconditionson
stageforsmallerensembles,likechambergroups,havebeenstudiedbyforinstance Barron
(1978),Marshallet al.(1978),DAntonio(1992),Chiang&Chen(2003)andSanders(2003).
Theseresultscannotbeseenas directlyvalid forimpressionsamongplayerin symphony
orchestras,since smallergroups areexpected tohave lessproblems with time delay and
obstructionof thedirectsound. Severalinvestigationsofacousticconditionsforsymphony
orchestrasarebasedonexperiencesfromconsultancyjobs,whereonlyaverylimitedsetof
hallsordifferentacousticconditionswereincluded,likeforinstanceShankland(1979),Gade
(1989c),Allen(1980),Benade(1984),Harkness(1984)andKanet al.(1995).Themusicians
absolutepreferenceforaparticularstageislikelytobesignificantlycolouredbyindividual
preferencesamongthemusicians. Fromstudiesofperceivedaudioqualityamonglistenersingeneral,Zielinskiet al. (2008)foundthatbiasduetoaffectivejudgementsmayresultin
errorsofup to40%with respectto the totalrange ofthescale. Thissuggeststhatonly
relativedifferencesinpreferencebetweendifferentstagesmaybevalidwhenstudyingthe
relationbetweenobjectivebehaviourandsubjectiveimpressions.Themostsignificantstudies
ofrelativechangeofpreferencearegivenbelow.
Some studies involved changing the acoustic conditions for one stage and asking the
musiciansabouttheperceivedimpressionofconditionsbeforeandafterthechange. Rindel
(1991) studied the effect of adding overhead reflectors on stage, Kahle & Katz (2004)
investigatedtheeffectofmakingthebackwallabsorbing,whileBerntson&Andersson(2007)
studiedhowchangesofthestageenclosureinaniterativeprocesswithplayerscontributedto
improvetheconditionsfortheplayers.Astudyby Halmrast(2000)focusedontherelevanceof
combfilteringinthefrequencydomainonperceivedsoundacrossthestageforonesymphony
orchestraplayingat twodifferentvenues. Theresultsfromthesestudiesare referredto in
moredetailinChapter5, thoughsuchsinglecasestudiesmayhavelowgeneralvalidityfor
severalreasons: theplayersmayhavebecomefamiliarwiththenewconditionsoveronlya
verylimitedtimeperiod. Iftheplayershaveadaptedtotheirexistingconditionsoverseveral
years,theperceivedchangeofconditionscouldalsobemisleading. Therefore,thechange
ofpreferencemayonlybevalidfortheparticularinitial/existingconditionseveniftheplayersweresufficientlyfamiliarisedwithnewconditions.
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Gade (1989c) carried out a study of three Danish symphony orchestras impressions of
acousticconditionsofnineperformancevenuesincludingtheirhomevenues.Thismeantthat
thedifferentstagesinvolvedwerejudgedbydifferentorchestras,exceptforonehallwhere
twooftheorchestrasregularlyperformed. Oneoftheseorchestraswentonatourwithinthe
UnitedKingdomandtheimpressionsofthevisitedhallswerealsostudied. Theinclusionof
differentorchestrasmakesitmoredifficulttodirectlycompareimpressionsofthenineDanish
halls inGadesstudy. Theplayersmayaswellhaveadapted totheirhomevenues,which
couldcontributetomaketheirjudgementslessvalidingeneralterms. ForhisUKstudy,the
impressionsbytheplayersmaysufferfrompoorvalidityandreliabilitysincetheplayersonly
visitedthesehallsonce. ThevenuesincludedinGadesstudyincludepurposebuiltconcert
halls,butalsosmallervenueswithshortmeasuredreverberationtimes.Thismeantthatvenue
typeand stageenclosure design bothvariedat the same time,making itmoredifficultto
isolatecauseandeffect.Similar,morerecentstudieswerecarriedoutbyCederlof(2006)and
Giovannini (2008), though thehallsstudiedbyCederlof (2006) includedonlypurpose-built
concerthalls(withinSweden). Theresultsfromthesestudiesarediscussedinmoredetailin
Chapter8.
Halmrast(2000)carriedoutmeasurementsofimpulseresponsesacrossthestagewithafull
symphonyorchestrapresent. Hefoundthat ifmeasuredresponsesshowedcombfiltering in
thefrequencydomain,itwouldindicatenegativecolourationeffectsperceivedbytheplayers
onstage.Theobservedcombfilteringwasduetoanearlyreflectioninterferingwiththedirect
sound(within-orchestra)sound. Ifthedelaybetweenthedirectsoundandthisreflectionwas
525ms,theperceivednegativeeffectsappeared tobemostprominent. Thistimeinterval
resultsinacombfilterwithabandwidthbetweencancelationscorrespondingtothecritical
bandwidthofourauditorysystem.Withnofurtherstudiesofthisphenomenon,itisdifficultto
sayifthecombfilterobservedistherealcauseoranindicationoftheproblemsreportedby
theplayers.SeeChapter5andAppendixDforfurtherdiscussionsofHalmrastsfindings.
Severalof theresultsfromthe studiesmentionedabovecanbe seenas contradicting, for
instancewithregardtotheeffectofdifferenttimearrivalsofearlyreflectionsandthebenefitsof
overheadreflectingsurfaces.Suchcontradictionsarelikelytoarisewhenstudiesinvolveonly
alimitedsetofhallsororchestras. Thestudiesmentionedabove,whichinvolvedmorethan
onestage,hadthedifferentstagesjudgedbydifferentorchestrasorbythehomeorchestras;it
isdifficulttoknowhowthepreferencesandadaptationwilldifferamongthejudgingorchestras
andtodrawconclusionsthatwillhavegeneralvalidity.
2.2.3 Laboratoryexperiments
Severalstudieshaveinvestigatedmutualhearingbetweenplayers.Thetolerancefordelayof
thedirectsound,audibilityofearlyreflectionsandpreferenceforlaterarrivingreflectionsare
amongothertopicsconsideredinlaboratorystudies.
Gade (1989b) studied how sound levels and delay of sound affected how two players
experiencedplayingtogether.Theeffectofearlyreflectionswasalsostudied.Thetwoplayers
weresittinginphysicallyseparatedanechoicchamberswithauralcommunicationprovidedby
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microphonesandloudspeakers.Threeviolinplayers,threecelloplayersandthreefluteplayers
participated. Thedirectsoundfromtheotherplayerwasdelayed,changedinlevelandlow
passfiltered. Thechangesofdelayand levelweredesignedtosimulatespecificdistances
betweenplayersandthelossathighfrequenciestosimulatetheobstructioneffectintroduced
bytheorchestra.Thesoundoftheotherplayerwasplayedfromoneloudspeakerinfrontofthe
playersandasetofearlyreflectionsandreverberantsoundwereintroducedbyaloudspeaker
verticallyabovetheplayers. Theresultsshowedthatadelayofdirectsounddelayedmore
than20mswasfounddisturbingbytheplayers.Suchadelaycorrespondstoa7mseparation
betweentheplayers. Alossofhighfrequencysoundandintroductionofreverberantsound
werefoundtomakemutualhearingmoredifficult. Forsomeofthe instruments, theresults
indicatedthatthesoundofonesowninstrumentcontributedtocompletelymasktheaudibility
ofearlyreflectionsupto20100ms. Therewasnovisualcontactbetweentheplayers.The
lackofvisualcuesmayhaveexaggeratedthenegativeeffectsofdelayeddirectsound. The
effectsobservedwithearlyreflectionsandreverberantsoundmayhavebeenaffectedbythe
simplifiedmethodofgeneratingthesesoundcomponentsinthelaboratory.
Guthrie(2008)performedsimilarinvestigationswithtwomusicianssittinginseparaterooms
playingtogether. Inadditionto transmittingsoundfromtheotherinstrumentandartificially
simulating a set of different room acoustic responses, cameras and displays were also
includedtoallowvisualcommunicationbetweentheplayers.Thevisualcommunicationwas
switchedonandoffasanexperimentalparameter.Theresultsindicatedthattheself-to-other
ratioinsoundlevelsismostcrucialforgoodcommunicationbetweentheplayers,followedby
visualcommunication.
Nakayama(1986)andSatoet al.(2000)foundthroughlaboratoryexperimentswithfivecello
soloistsandonealto-recordersoloistthatthepreferreddelayofareflectiondependedonthe
tempoofthemusicalmotifplayed. Alongerdelaytimewaspreferredfortheslowestmotif.
Nakayama (1986) foundapreference forreflection fromabove,whensimulating twoearly
reflections. AcomparablestudybyNakayama&Uehata(1986)showedthatareflectionin
themedianplanecouldcreateaperceivedsoundimageinthefrontaldirection. Aperceived
soundimageinfrontaldirectionswasbelievedtobebeneficialfortheperformergivingthe
impressionthattheirsoundwasbeingdirectlypropagatedtothelistener.
Meyer (1986)studied players sensitivity toanearlyreflectiondepending ondirection and
musicalinstrumentbeingplayed. Theresultsindicated thatat1kHzthemusicianswillbe
moresensitive to reflectionsarriving fromabovecompared toreflectionsarriving fromthe
sidesordiagonallyfromabove.Thiswasfoundbetocausedbymaskingeffectsoftheirown
instrument.Thisobservationledtotheproposalofabeneficiallayoutforoverheadreflectors,
asshowninFigure2.1: aflat reflectorabove thestringswould enable reflectionsbackto
thestringplayersfromthedirectionfromwhich theyweremostsensitive. Atilted reflector
abovethewoodwind(facingtheaudience)wouldreflectsoundfromthestringplayersdown
towardsthewoodwindplayersverticallyfromabove,while reflectingsoundfromwoodwind
diagonallydowntowardsthestrings.Suchanarrangementwasbelievedtohelpthewoodwind
playershearthestringswithoutwoodwindsbecomingtooloudforthestringplayers. Buton
theotherhand,ahorizontalreflectingsurfaceabovethestringplayerscanmakeitdifficultto
hearotherstringplayersatafartherdistance,sincethesensitivityforthereflectionfromones
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owninstrumentcouldbehigher thanreflectionsfromplayersat adistance. Thisis further
discussedinSection5.5.2.
WindsStrings
Figure2.1:LongsectionviewofreflectorabovestringsandwoodwindsasproposedbyMeyer(1986).
Naylor & Craik (1988) carried out investigations of hearing oneself and other players.
Musiciansinananechoicchamberplayedalongtopre-recordedmusic. Differentversionsof
pre-recordedmusicwereusedtosimulatedifferentacousticconditions.Theirresultsshowed
thatincreasingthetemporalandpitchdifferencebetweensoundofselfandothers,improved
theimpressionofhearingselfandotherplayers.Theoptimumtotallevelofotherswasfound
tobewithin23and+5dBArelativetolevelofownsound. AccordingtoNaylor(1985),this
intervalis fortriplecounterpointplaying. Forunisonandsinglecounterpointtherespective
intervalswerefoundtobe15to+5and21to+7dBA.Naylor(1988)suggestedthatthe
levelofonesowninstrumentwasalmostindependentoftheroomandthattheroommainly
controlled the levelofothers. The levelbalancebetweenselfandotherswas found tobe
important. ThisagreeswellwithGadesfindingwithregardtoaudibilityofearly reflections
ofonesowninstrumentasreferredtoabove. Naylorfoundthatreflectorsnearasymphony
orchestrawere founduseful forincreasing the levelofothersand the ratioofearly tolate
soundlevel,butforsmallenclosuresabsorptionmayinsteadbeneededtoavoidexcessively
high sound levels. Reverberation was also found useful for raising the perceived level of
others.Stringplayersatreardesks(atthesidesofthestage)werementionedasparticularly
challengedplayerswithregardtohearingwithintherestoftheirsections,andcouldbenefit
fromreceivingreflections. Ternstromet al.(2005)foundcomparablelimitsforlevelofothers
fromalaboratorystudywithsingers:thesingersperformedbestwithregardtointonationwith
soundlevelofowntheirvoicebeingwithin15dBto+5dBrelativetotheothers.Thesound
leveloftheothersingerswasestimatedbyrecordingthesoundatboththeearsofthesingers
duringanoperaperformance(byuseofminiaturemicrophones).
Ueno&Tachibana(2003) established asystem forregenerating roomimpulse responses
fromrealhallsinananechoicchamber.Thisenabledarapidswitchbetweendifferentplaying
conditionsfortheplayersbasedonrealroomresponses.Impulseresponsesfromrealspaces
werecollectedbyuseofanomnidirectionalsourceandsixmicrophonesfourinthehorizontal
(front, back and left and right) and two in the vertical plane (below and above). These
measuredresponseswereconvolvedwiththedirectsoundfromtheinstrumentplayedinthe
anechoicchamber. Theresultingsoundwasplayedback in the sameanechoicchamber
fromsixloudspeakerslocatedinthesamedirectionsasthesixmicrophonesusedtocapturetherealroomresponse.Thesynthesisedimpulseresponsesintheanechoicchambershowed
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goodagreementwiththerealimpulseresponses,alsoforcalculatedacousticmeasuresbased
onthe impulseresponses. Thesimulatedimpulseresponsesenabledtheearlyreflections,
reverberationanddiscretelatereflectionstobecontrolledindependently.Initialresults(Ueno
et al., 1998) indicated that differences in the compositionofearly reflectionswere hardly
recognised by the players. Results from Ueno& Tachibana (2003) showed that for solo
playing,themusicians(threeflute,oneclarinet,twooboe,threeviolinandthreeviolaplayers)
preferredalowlevelofearlyreflectionsandmoderatelevelofreverberantsound.Withregard
toadiscretelatereflection(arrivingat250ms),theresultsindicatedthatsuchareflection
waspreferredaslongasitwasatamoderatelevel.Uenoet al.(2004)studiedtwoplayers
playingtogetherinseparatedanechoicchambersusingthedeveloped6-channelsimulation
system. Theresultsindicatedthatbothearlyreflectionsandreverberationshouldbeatan
optimum level for the most preferred conditions for playing together. This was basedon
impulseresponseonanemptystagewithasource-receiverdistanceofapproximately6.7m.
Withregardtothevalidityofthelaboratorystudies,investigationsofmutualhearingbetween
twoplayerswithouttherestoftheorchestrapresentmayhaveresultedinunnaturalconditionsfortheplayersorconditionsthatbetterapplytosmallerensemblescomparedtosymphony
orchestras.Theobstructioneffectbyplayerssittinginbetweenandmaskingeffectscausedby
interferingsoundfromotherinstrumentswillnotbefullyencounteredundersuchconditions.
OnlyNaylor&Craik(1988)appeartohaveusedinterferingsoundforstudiesofmutualhearing.
TheinvestigationsbyGade(1989b)includedhighfrequencyattenuationofthedirectsoundto
simulatetheobstructioneffect.Theomissionofotherplayerscouldrepresentconditionsmore
valid forsmallerensembles than forsymphonyorchestras. The limitednumber ofplayers
involvedandthenumberofloudspeakersusedforthereproductionofearlyreflectionsand
reverberantsoundmaywell have contributed toreducedvalidity of the results from these
laboratoryinvestigations.Anothercriticalfactormaybethemusicalrepertoirechosenforthe
studies.Gade(1989b)used,inparticular,theTrioSonatabyJ.S.Bachandthe40thSymphony
byW.A.Mozartassourcematerial. OnthecontraryGuthrie(2008)usedarepertoirewhere
the structureand durationofnotesproduced by the individualplayersare lesspredicable
(C.Wolff). Suchsignificantdifferencesinsourcematerialscanhavecontributedtodifferent
conclusionsregardingtheimportanceofdifferentacousticalaspects.Thefindingswithregard
totheaudibilityofearlyreflectionsof onesowninstrumentmaybesufficientlyvalid, since
anintroduction ofother playerswillmakeearly reflectionsofonesownsoundeven more
inaudibleduetomaskingeffects.Thisfindingsuggeststhatsurfacessurroundinganorchestra
willmainlycontrolthelevelofothers,notthelevelofonesowninstrument.
2.3 Proposedacousticmeasures
Someofthelaboratorystudiesmentionedaboveledtoproposalsofacousticmeasuresto
assess the acousticconditionsforthe performers. Belowfollowsmoredetail onthemost
significantmeasuresproposedforassessingtheacousticconditionsfortheperformers: the
ST measures. OtherproposedmeasureslikeMTF andRR160arepresentedattheendof
thissection.
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Thefirstdedicatedstageacousticmeasureswereproposedby Gade(1989c)andlaterrevised
inGade(1992)thesupportST measures.ThefollowingSupportmeasures,ST havebeen
proposedbyGade(1992): STearly (previouslydenotedST 1)toassessensembleconditions,
STlate forassessing the impressionof reverberationand STtotal forassessingsupportfrom
the room forsoundfromthemusiciansown instrument. TheST measuressumthelevel
ofsoundreflectionsreturningbacktoamusicianonstagefromanydirection,byuseofan
omnidirectionalloudspeakerandmicrophone. Thesumofreflectionsistakenwithindifferent
time intervals relative to the emissionofsound. The time intervals forSTearly, STlate and
STtotal are 20100, 1001000 and 201000ms respectively. The microphone should be
1m fromthecentreofthesoundsourceat1 mheight, toemulate aninstrumentandthe
roomacousticresponseof itasreceivedatthemusiciansears. Thecombinedlevelofthe
measureddirectsoundandthestagefloorreflectionisusedasthereferencelevel,summed
withinthetimeinterval010msfromthemeasuredimpulseresponse. Equations(2.1)(2.3)
arethe mathematicaldefinitionsof STearly, STlate andSTtotal. For theDanishhallsstudied
byGade(1989c),STearly showedcorrelationatasignificantlevelwithsubjectivemeasures
representingmutualhearing (ensemblemeasures),whileSTlate (replacingCS asproposed
inGade(1989b))showedsignificantcorrelationwithperceivedreverberation. Gade(1989c)
alsoproposedameasurecalledEEL (EarlyEnsembleLevel).Thismeasurewasobtainedby
measuringacrossthestageusingtwomicrophones,withonemicrophoneforthereference
levelandonemeasuringmicrophonefortheresponseacrossthestage. Equation2.4shows
themathematicaldefinitionofEEL. Em istheenergyresponseatthemeasuringmicrophone
witht =0referringtotimeforemissionofsound.Duetotheabsenceofsignificantcorrelations
betweenEEL andsubjectivemeasures,EEL waslateromitted(Gade,1992).SeeSection7.7
formoredetailsonmeasurementofST onrealstages.
E(20100ms)STearly= 10 log10 dB (2.1)E(010ms)
E(1001000ms)STlate= 1 0 log10 dB (2.2)E(010ms)
E(201000ms)STtotal= 1 0 log10 dB (2.3)E(010ms)
Em(080ms)EEL = 10 log10 dB (2.4)E(010ms)
Gade (1989c) investigated thevalidityof theseobjective measures through threedifferent
studies.HisfirststudyincludedthreeDanishorchestrasimpressionsofninevenuesincluding
theirhomevenues,andhisthirdstudyinvestigatedhowanexistingstagecouldbeimproved
bymodifyingthestageenclosure. Forthesetwostudiessignificantcorrelationswerefound
betweenST measuresandsubjectivemeasures.Onthecontrary,theresultsfromhissecond
studywithoneoftheDanishorchestrasvisitingeighthallswithintheUnitedKingdomindicatedthatSTearly didnot correlatewellwithsubjectivemeasures. Asdiscussed inSection2.2.2
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Gadesfirstandsecondstudymaysufferfrompoorvalidityandreliability. ThevalidityofST
isdiscussedinmoredetailinChapter7.Otherstudieshavecoveredthetechnicalaspectsof
ST ,consideringtheeffectofthetimelimitsused,andtheimportanceofhavingchairsonthe
stagewhilecarryingoutthemeasurements. ResultsbyvandenBraaket al.(2005),Jeon&
Barron(2005),OKeefe(1995)andOKeefe(1994)indicatethatthedefinitionof ST andhow
itshouldbemeasuredcontributetoreducedreliabilityofST .Thisisdiscussedinmoredetail
inSection7.7. Kimet al.(2005)andGiovannini&Gade(2007)foundthat STearly wasnot
veryresponsivetochangestothestageenclosure,buttheperceivedimpressionsofthese
changeswerenotinvestigated.
Naylor (1988) proposed the use ofmodulation transfer functions (MTF) measuredacross
the stage toevaluate conditions formutual hearing. Thiswas basedon the use ofMTF
for assessing speech intelligibility, as proposed by Houtgast & Steeneken (1973). The
mathematicaldefinitionof themodulation transferfunction,MTF,asusedbyNaylor(1988)
wasbasedon Houtgast&Steeneken (1973). InHoutgast&Steeneken (1973), MTF was
appliedtoperceivedspeechintelligibilitywhereroomreverberationandthebackgroundnoisecontributeto reduce thecalculated speech intelligibility. Naylor (1988)setthebackground
noise level to represent the levelof interferingsound from otherplayers. In thisway the
communication channel between two players could be assessed taking into account the
influenceofdisturbingsound.Nostudiesbyothershavebeenfoundwhichhaveinvestigated
thevalidityofNaylorsproposedmethod.
Griesinger(1995)proposedameasurecalledrunningreverberationforassessingperceived
reverberationduringmusicalperformance. Equation(2.5)showsthemathematicaldefinition
ofRR160. NoinvestigationshavebeenfoundwhichstudythevalidityofRR160otherthan
Griesinger,butKahle&Jullien(1994)foundobjectivemeasurescomparabletoRR160 tobest
correlatewiththesubjectiveimpressionofreverberance.
E(160320ms)RR160 = 10
log10 dB (2.5)E(0160ms)
vandenBraak&vanLuxemburg (2008)proposedameasuredenoted LQ740 forassessing
acousticconditionsforconductorofasymphonyorchestra.Thismeasurewasalsoproposed
toberelevantfortheplayers.SeeSection2.4formoredetails.
vonBek esy(1971)proposedtheconceptofauditorybackwardinhibitionbasedonlaboratory
experimentsthatindicatedthatdiscretereflectionsarrivingwithin60200msafterthedirect
sound could contribute to reduced clarity of sound. Based on the concept of auditory
backwardinhibition, itwassuggestedinAshley(1979)andAshley(1981)thatthearrivalof
suchreflectionscouldexplainthepreferenceforcertainconcerthallstagesamongorchestral
musicians.Thiswasnotdevelopedtodefineanacousticmeasure.Blauert&Tttemann(1980)
triedtoreproducethelaboratoryexperimentsinitiallycarriedoutbyvonB esy(1971).Theirek
resultsdidnotshowanyevidenceofthemechanismauditorybackwardinhibition. Afterthe
publicationbyBlauert&Tttemann(1980),auditorybackwardinhibitionhasnotbeenfound
mentionedinliterature.
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Two objective measures were also proposed at an early stage of this project, based on
monophonicomnidirectionalimpulseresponsesmeasuredonstagewithoutafullsymphony
orchestra present. The first measure proposed (EB Ensemble Balance) was designed
forassessingthebalancebetweenearlyreflectionsfromanotherplayercomparedtoearly
reflectionsfromonesowninstrument.Thesecondmeasure(EMDT Early-MidDecayTime)
wasdesignedforassessingtemporalclarityofsoundfromforwardintegrationofthemeasured
acousticresponse,mimickingthetemporalintegrationinthehumanauditorysystemasused
by Cremer (1989). From the investigations of real halls and perceived conditions, these
objectivemeasuresdidnotshowanysignificant correlations withthe subjectivemeasures
investigated. ResultsbyGade(1989c)andNaylor(1988)indicatethatearlyreflectionsfrom
ones own instrument will bemasked by the direct soundofones own instrument. This
may explainwhy EB wasnot found significantwhen relating to subjective characteristics.
The low significance of EMDT may relate to both its mathematical definition and how it
wasassessed forthisprojectwithoutmusicianspresentonstage. Thesetwoproposed
measuresarethereforeherenotdescribedanyfurther,butthedefinitionandfailureofthese
measures(describedinfurtherdetailinSection 9.5)mayproviderelevantinformationforfuture
investigations. SeeBarron&Dammerud(2006)andDammerud&Barron(2007)formore
detailsonthesemeasures.
Theobjectiveacousticmeasureslistedabovehavemainlybeeninvestigatedbytheauthors
who originally proposed the measure(s). Only the ST measures have been investigated
by others, but mainly regarding the physical behaviour of the measures. Nostudies are
foundintheliteratureregardingthecorrelationbetweentheacousticmeasuresandsubjective
characteristics,wherealargenumberofprofessionalsymphonyorchestraplayinginpurpose-
builtconcerthallshasparticipated.
2.4 Effectofstageenclosureforconductorandaudience
Whenstudyingpreferredconditionsamongtheplayers,itisrelevanttostudyhowthedesign
ofthestageenclosureaffectstheconditionsfortheconductorandtheaudienceaswell.This
sectioncoversthemainresultsfoundintheliteraturewithregardtooptimumstageenclosure
designforthesetwogroups.
InMeyer (1994)andMeyer (2008)conditionsfortheconductors(ofsymphonyorchestras)
werestudied. AccordingtoMeyer(1994)theacousticconditionsattheconductorsposition
areimportantforreachingawell-balancedorchestrasoundfortheaudience. Hefoundthat
anoverhead reflectorabove the centre of the orchestra couldlead toa lackofperceived
reverberant hall sound and that it could lead to strings becoming too loud, in particular
comparedtowoodwindinstruments.Thefollowingconditionswerefoundtoresultinfavourable
conditions for the conductor: wallsatthesideofthestage, a largevolume infront ofthe
conductor(exposedstage) to linkwith therestof thehallvolume,andoverheadreflectors
designedtomainlyreflectwoodwindsoundtowardstheconductor.
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vanden Braak&vanLuxemburg (2008)experimentedwiththeeffectsofstageenclosure
by lookingat twospecificstages. Lookingat values of ST did not revealany significant
differencesinacousticconditionsforthedifferentconfigurationsanddidnotagreewiththe
impressionsamong the musicians and conductor performing on these two stages. They
proposedanewmeasure(furtherinvestigatedinvandenBraaket al.(2009)),calledLQ740,
asdefinedinEq.2.6.Thismeasurerepresentstheenergyratioofmeasuredearlyreflections
within 740ms (relative to arrival of the direct sound) and measured late energy level
within 40ms. The measurements were carried out with the soundsource atdifferent
positionswithintheorchestraandareceiverattheconductorsposition(bothomnidirectional).
TheirmeasuredvaluesofcalculatedvaluesLQ740 agreedwellwiththeactualconductors
impressionsoftheacousticconditions,aswellastheimpressionsamongtheplayers.
E(740ms)LQ740= 10 log10 dB (2.6)E(40ms)
Insomecasesareflectorabovetheorchestramaybeneededtoraisethesoundlevelsor
improvethe balanceof theorchestrainstruments forsomesectionsof theaudiencearea.
Cremer&Muller(1982)foundthatmaximum30%ofthespaceabovetheorchestrashould
becoveredbyreflectorsforthe audiencespointof view, whereasBeranek(1992)setthis
limitat50%. Meyer (1977)foundtheceiling(oroverheadreflector)tobeimportantforthe
brilliance,whereasthesidewallswereimportantforvolumeandsonority. Bradley(1996)found
fromhisexperimentswithaddedstageenclosures(shells)onthreeexistingstages,thatthe
changesofobjectiveacousticconditionsweremoresignificantonstagecomparedtoin the
audience. Onlylookingatobjectiveacousticmeasurescouldforthisstudyhavelimitedthe
apparentchangesfortheaudience.
Griesinger (2006) found that too high a level of early reflections, or too low a level of
direct sound, could contribute to an impression of a remote and muddy sound (lack of
definition/clarity)fortheaudience.InGriesinger(2007),moredetailswereprovidedregarding
thishypothesis.
Miller(1987)carriedoutexperimentswithrisers(raisedplatforms)forbrassandpercussion
andfoundthatriserscontributedtoraisethedirectsoundleveloftheseinstruments.Insome
casesthisledtobrassandpercussionbeingtooloudcomparedtostringsandwoodwinds,
butwithbrassandpercussiononaflatfloor,thedirectsoundlevelsfromtheseinstrumentsinthestallsareawerefoundtobetoolow.
Theseresultssuggestthatfromtheconductorsandtheaudiencespointofview, thestage
enclosureshouldnothaveamajor,solidreflectingsurfaceatlowheightabovetheorchestra.
The resultsalsosuggest that sidewallsclose totheorchestraare beneficial and that the
stageenclosureshouldnotbetooreflectiveorenclosedaroundtheorchestra.Smallerareas
of reflectorabove the orchestra can be beneficial for the level balance between different
instrumentsandperceivedclarity.
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2.5 Approachesusedforthisstudy
The literature review has shown thereare stillmany unresolvedquestions with regard to
how musicians relate to acoustic conditions on concert hall stages and what their main
concernsare. Aqualitative understanding ofhow musicians relate toacousticconditions
couldbeessentialbeforetryingtofindobjectivequantitativemeasuresthatcorrespondwith
their ratingofdifferentacousticaspects. A focusonquantitativephysicalmeasurescould
result in what couldbe describedas a positivistic approach, asused in social sciences.
PositivismhasbeendescribedbySmith(1998)asfollows: Positivistapproachesareunited
intheirattempttoeradicatemetaphysicsandotherhangoversfromrationalismfromscientific
knowledge. Inparticular,theyarestronglyattachedtogroundingallourknowledgeofthings
in perceptions, impressions and sensations as evidence of their tangible and observable
existence. Positivism hasbeenseenrelated torationalismasdefinedbySmith (1998):
In knowledge construction rationalism is often seen as opposed to experience (with the
strongest contrastbeingbetween rationalismand empiricism). Forpositivists, rationalismwasthesourceofmetaphysicalspeculationandit undermined thehealthysenseofdoubt
whichempiricismwassupposedtoengendermanyfailedpositivistswereattackedfortheir
rationalist leanings. Reference topositivisticapproacheshavebeenmadeforinstancein
musicalsciencebyDuffin(2007).Thedifferenttemperamentsofnotesinmusicalscaleshave
moreorlessdisappearedaftertheintroductionoftheequaltemperament.Equaltemperament
ismathematicallyelegant, but lacks thepossibility ofharmonic variationbetweendifferent
keys. From Duffin (2007): In general terms positivism looks for empirical data to justify
knowledgeorbeliefs. Asaresultitexcludesthingsthatcannotbestudiedbyquantification
orthatdonotfit theoriesassembledbydocumentedevidence. Thismeansthatsomething
socomplexandirrationalasthedivisionofsoundsintoamusicalscalewasboundtoprefer
theorderandapparentsimplicityofequaltemperament. Blauert(2007)raisedaconcernfor
acousticiansnothavingasufficientunderstandingofthehigher(lessquantifiable)levelsof
communicationwithinacousticspaces.Acousticiansarenormallytrainedinnaturalsciences,
whilemusicianshaveamusicaleducationwhichincludesverylittlethatisrelatedtonatural
sciences.Theremaythereforebeariskofstudiescarriedoutbyacousticianshavingafocus
onthephysicalaspectswhilepayinglessattentiontootherlesseasilyquantifiableaspects.
Withsuchapositivisticapproachtherecouldbeanoverlyoptimisticbeliefintheimportance
ofthequantifiableaspects.
Themainaimsforthisprojectweretobetterunderstandhowstageacousticconditionsare
perceivedbysymphonyorchestramusiciansandhowauditoriumandstageenclosuresshould
bedesignedforoptimumauralworkingconditionsforthemusicians.Fromtheliteraturereview
above,fewsystematicstudiesofacousticconditionsspecificallyforsymphonyorchestrashave
beencarriedout. Studiesofphysicalconditionsimposedbytheorchestraconfigurationhave
beenverybrief. Laboratorystudiescarriedouthavenotincludedafullsymphonyorchestra,
only a few playersor single players. For studies of specificstages there are only a few
investigations carriedout,whichmayhavelowvaliditycausedbythe halls andorchestras
covered. Forthisproject,laboratoryandmodellinginvestigationshavebeenlimitedtoscale
andcomputermodellinglaboratoryinvestigationsincludingprofessionalmusicianswerenot
possibleduetoalackofananechoicchamber. Studyingimpressionsofacousticconditions
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with a limited set of players and different acoustic conditions, will normally lead to high
uncertaintiesassociatedwiththeirjudgements. Withregardtorelationsbetweensubjective
andobjectivemeasures,mostpreviousstudieshaveonlyinvestigatedimpressionsofhome
stagesorhallsvisitedoccasionally. Thelevelofadaptationbytheplayerstocertainacoustic
conditionscouldhavecontributedtoreducedvalidityofthesestudies.
Theearlypartofthisthesiscoversinvestigationsofhowacousticconditionsareexperienced
bythemusicians. Byuseofquestionnairesanddialoguewithmusicians,theirpointofview
hasbeenstudied.Thisstudyisfollowedbyinvestigationsofphysicalconditionsonstageand
howthesephysicalconditionsarelikelyaffectsubjectiveimpressionsliketheabilitytohear
otherplayersclearly.Tominimisetheeffectofuncertaintiesrelatedtospecificcases,generic
acousticconditionsonstagehavebeenstudiedobjectively(byuseofscaleandcomputer
modellingaswellasanalyticalstudies)withreferencetogeneralfindingswithinthefieldof
soundperception (psychoacoustics). With theseapproaches, the investigation will not be
limited toexistingacousticmeasures(quantitativemethods)withthe riskof too limitedan
approach. Inaddition tosuchinvestigations, theplayers impressionsofhallsvisitedonaregularbasishavebeenstudied.Thesetwoapproachesavoidenquiringaboutimpressionsof
acousticconditionsonlyexperiencedoccasionally.Whilethemajorityofsubjectivedataused
hereisforhallsvisitedregularly,someimpressionsofhallsvisitedonlyoccasionallyhavealso
beenincluded.
Theaboveapproachesweremotivatedbysearchingforrelationsbetweenobjectiveacoustic
conditionsandperceivedconditions,byuseofquantitativebutalsomorequalitativemethods.
Itwillalsoberelevantto studyhowobjectiveacousticconditionsshouldbeassessed. In
particular, should the acousticconditionsbeassessedwitha full symphonyorchestra (or
equivalent group of people) present? Scale modelling have been used in this study to
investigate indetail the acousticconditions within anorchestra configuration and how the
roomimpulseresponsesonstageareaffectedbythepresenceoftheorchestra. Computer
modellingwasusedtostudyhowdifferentstageenclosuredesignsaffectacousticconditions.
Measuredresponsesonexistingstages(withoutafullsymphonyorchestrapresent)werealso
studied,tofindthemostvalidandreliablewaytoassessrealobjectiveacousticconditions.
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Chapter3
Musiciansimpressionsof
acousticconditions
3.1 Introduction
Togetabetterunderstandingofhowmusicianswithinsymphonyorchestrasexperienceand
relate to the acoustic conditions on stage, the first subjective study involved distributing
questionnaires to eight symphony orchestras six English and two Norwegian. The
six English orchestraswere: BBC Philharmonic, Bournemouth SymphonyOrchestra, City
of Birmingham Symphony Orchestra, Hall London Philharmonic Orchestra and Royale,
PhilharmonicOrchestra. ThetwoNorwegianorchestraswereOsloPhilharmonicOrchestra
andTrondheimSymphonyOrchestra.Theresultsfromthisstudyarereportedinthischapter,
while the results from the second subjective investigation are presented in Chapter 8.
Musicians impressions of stageacoustic conditionshave previously been investigated by
severalauthors. Gadeinvestigatedthisthroughbothlaboratoryexperimentsandinterviews
with musicians (Gade (1981)and Gade (1989b)). Whichaspectsofstageacoustics that
appearmostimportantforthemusicianswereinvestigatedthroughquestionnairesby Genta
et al. (2007b).LaboratoryinvestigationshavealsobeencarriedoutbyNaylor&Craik(1988),
Meyer(2009)andUenoet al.(2004).Alotoffindingscameoutofthesestudiesinbriefthe
resultsconsistentlyshowthatthemostimportantaspectsfortheplayersappeartobehearing
eachotherclearly, withhearing ofothers well balancedwith theirown sound. Asuitable
amountofacousticresponsefromtheauditoriumalsoappearscrucialforthem.
Thequestionnairedistributedtotheeightorchestrasconsistedofquestionsrelatedtostaging
conditions(likerisersandspaceavailable),acousticandnon-acousticconditions. Someof
thequestionswereopen(wheretheplayerscouldcommentfreely),whereasformostofthe
questionsthemusicianswereaskedabouttheirpreferencesonbipolarsemanticdifferential
scales (Likert rating scales), ranging 15. For some of these rating questions they were
asked to further comment on their preferenceor experiences. The musicians were alsorequestedtolistthehalltheyrememberasprovidingthebestacousticconditionstheyhad
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everexperiencedintheircareer,alongwithcommentsonwhytheypreferredthisparticular
hall.TheBritishorchestraswereaskedtoratethehallstheyregularlyperformin,withrespect
tooverallacousticimpression(OAI),with33hallsbeingjudgedbytheorchestrasoverall.One
oftheNorwegianorchestraswasaskedtorate12hallswithinEurope,USAandJapanwhich
theyhavevisitedoverseveraloccasions(34times).Theywereaskedtoprovidereasonsfor
theirleastandmostpreferredhall.Someofthequestionsmentionedherewerenotincluded
foralltheorchestras,buttheresponserateonallindividualquestionswassufficienttodraw
someconclusions.
Theresponsesfromthedifferentinstrumentgroups(string,woodwind,brassandpercussion)
have been compared. For the purpose-built concert halls regularly visited, the ratings
havebeencomparedwithavailableobjectiveacousticmeasuresandarchitecturalmeasures
obtainedfromhalldrawings.Someofthehallswereratedbymorethanoneorchestra.This
hasallowedinvestigationoftheconsistencyofjudgementsofoverallacousticimpression.The
statisticalanalysesweredoneusingSPSSversion14andMATLABR2006a.
Thechapter isorganisedintothreemajorpartswithdiscussion/conclusionsectionsat the
endofeachpart.Thefirstpartcoverstheopenquestionsinthequestionnaireincludingtheir
favouritehalls,whilethesecondpartcoversthepreferencequestions. Inthethirdpart, the
hallsratedbytheplayersarestudiedwithreferencetoobjectivemeasuresrelatedtothehalls.
3.2 Questionnairemethod
QuestionnairesconsistingoftwosidesofA4weredistributedtotheplayersbytheirorchestra
administration. Typicallytheyweregiventwoweekstorespondandreturn thequestionnaire
backtotheadministration. Theirresponsesonindividualhallswerebasedonmemory. The
questionnaireswereinitiallypilotedwithasetofplayersandorchestrarepresentatives.
Thetopofthequestionnairecontainedabriefintroductionandaskedwhichinstrumentthey
playandhow manyyears theyhavebeenplayingprofessionally inasymphonyorchestra.
The bodyof the questionnaire contained preference and open questions. The details on
thesequestions are given in respectivesectionsbelow. See AppendixB fora sample of
thequestionnairedistributed.
3.3 Questionnaireresultsingeneral
Intotal 180 playersresponded108 stringplayers (60 %), 28woodwind players(16%),
32brassplayers(18%)and11percussionplayers(6%). Thenumberof responseswithin
eachorchestravariedfrom5to55(responseratesof681%).
With regard to years of experience as professional symphony orchestra musician, theaveragesforthedifferentinstrumentgroupswere:21yearsforstringplayers,24forwoodwind
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players,22 forbrassplayersand27yearsforpercussionplayers. Amongall theplayersthe
averagewas22yearsofexperience,withamaximumof45yearsandaminimumof1year.
Tenplayers(6%)reportedtheyhadlessthan5yearsofexperience. Thisindicatesthatthe
playerswhorespondedhaveconsiderableexperience.
3.4 Openquestions
3.4.1 Non-acousticissuesimportantonstage
Theplayerswereasked: Whatnon-acoustic issuesaresignificanttoyouthatdifferentiate
between the hallsyouplay in (suchas visibilityofotherplayers, lighting, thermal comfort
etc.)? Table 3.1 shows the relative frequencyofdifferentnon-acoustic issuesmentioned
assignificantbytheplayers. Theresultsshowthattemperatureandairqualityareofmost
significancetothem,withabouttwothirdsoftheplayersfindingthisimportant.Notonlyisthis
forcomfortreasons,butalsoforinstrumentconditionsseveralwoodwindplayersmentioned
problemswiththeirreedsindryhalls. Lightingismentionedequallyfrequently. Visibilityand
spaceismentionedbyaboutonethirdoftheplayers.Beingabletoseetheconductor,principal
andleadingplayersappearsasimportantfortheplayers,especiallyifauralcuesarenoteasy
tohear.20%oftherespondentsmentionedthatstageconditionsareimportant. 10%ofthe
playersmentionedstaging(risersandoverallstagedesign)assignificant. Somementioned
beingabletogetonandoffthestagesafely(noholesinthestageflooretc.),andtheflexibility
thestageoffersfortheplayerstoarrangethemselvesastheywish.Backstagefacilities,quality
ofnearbyrestaurants,contactwiththeaudienceandhearingeachotherwerealsomentioned,
butonlybyafewplayers.
Table3.1:Relativefrequencyofnon-acousticissuesmentionedbytheplayers.