stage harmonic for acoustics orchestra phd 2010 dammerud j

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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.

stage harmonic for acoustics orchestra phd 2010 dammerud j

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