Room acoustics

389 Pages·2009·7.03 MB·English

by  Heinrich Kuttruff

Room Acoustics
Fifth Edition

Room Acoustics
Fifth Edition
Heinrich Kuttruff
Institut für Technische Akustik, Technische
Hochschule Aachen, Aachen, Germany
Firstpublished1973
byElsevierSciencePublishersLtd
Secondedition1979
byElsevierSciencePublishersLtd
Thirdedition1991
byElsevierSciencePublishersLtd
Fourtheditionpublished2000
bySponPress
Thiseditionpublished2009
bySponPress
2ParkSquare,MiltonPark,Abingdon,OxonOX144RN
SimultaneouslypublishedintheUSAandCanada
byTaylor&Francis
270MadisonAvenue,NewYork,NY10016,USA
This edition published in the Taylor & Francis e-Library, 2009.
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©1973,1979,1991ElsevierSciencePublishers;
1999,2000,2009HeinrichKuttruff
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BritishLibraryCataloguinginPublicationData
Acataloguerecordforthisbookisavailable
fromtheBritishLibrary
LibraryofCongressCataloginginPublicationData
Kuttruff,Heinrich.
Roomacoustics/HeinrichKuttruff.—5thed.
p.cm.
Includesbibliographicalreferencesandindex.
1.Architecturalacoustics.I.Title.
NA2800.K872009
729(cid:1).29—dc22 2008051863
ISBN 0-203-87637-7 Master e-book ISBN
ISBN10:0-415-48021-3(hbk)
ISBN10:0-203-87637-7(ebk)
ISBN13:978-0-415-48021-5(hbk)
ISBN13:978-0-203-87637-4(ebk)
Contents
Preface to the fifth edition ix
Preface to the fourth edition xi
Preface to the first edition xiii
Introduction 1
1 Some facts on sound waves, sources and hearing 7
1.1 Basicrelations,thewaveequation 7
1.2 Planewavesandsphericalwaves 9
1.3 Energydensityandintensity,radiation 14
1.4 Signalsandsystems 16
1.5 Soundpressurelevelandsoundpowerlevel 22
1.6 Somepropertiesofhumanhearing 23
1.7 Soundsources 27
References 34
2 Reflection and scattering 35
2.1 Reflectionfactor,absorptioncoefficientand
wallimpedance 36
2.2 Soundreflectionatnormalincidence 37
2.3 Soundreflectionatobliqueincidence 42
2.4 Afewexamples 44
2.5 Randomsoundincidence 52
2.6 Reflectionfromfinite-sizedplanesurfaces 55
2.7 Scatteringbywallirregularities 59
References 66
vi Contents
3 Sound waves in a room 67
3.1 Formalsolutionofthewaveequation 68
3.2 Normalmodesinrectangularroomswith
rigidboundaries 71
3.3 Non-rigidwalls 79
3.4 Steady-statesoundfield 83
3.5 Frequencyandspatialaveraging 91
3.6 Decayingmodes,reverberation 94
References 99
4 Geometrical room acoustics 101
4.1 Enclosureswithplanewalls,imagesources 102
4.2 Thetemporaldistributionofreflections 109
4.3 Thedirectionaldistributionofreflections,
diffusesoundfield 114
4.4 Enclosureswithcurvedwalls 116
4.5 Enclosureswithdiffuselyreflectingwalls,
radiosityintegral 121
References 126
5 Reverberation and steady-state energy density 127
5.1 Basicpropertiesandrealisationofdiffuse
soundfields,energybalance 128
5.2 Meanfreepathandaveragerateofreflections 133
5.3 Sounddecayandreverberationtime 137
5.4 Theinfluenceofunequalpathlengths 141
5.5 Enclosuredrivenbyasoundsource 145
5.6 Applicationoftheradiosityintegral 148
5.7 Soundpropagationasadiffusionprocess 153
5.8 Coupledrooms 154
References 158
6 Sound absorption and sound absorbers 160
6.1 Theattenuationofsoundinair 161
6.2 Unavoidablewallabsorption 163
6.3 Soundabsorptionbymembranesand
perforatedsheets 164
6.4 Resonanceabsorbers 167
6.5 Helmholtzresonators 171
6.6 Soundabsorptionbyporousmaterials 177
Contents vii
6.7 Audienceandseatabsorption 188
6.8 Miscellaneousobjects 194
6.9 Anechoicrooms 199
References 202
7 Subjective room acoustics 204
7.1 Somegeneralremarksonreflectionsand
echoes 208
7.2 Theperceptibilityofreflections 210
7.3 Echoesandcolouration 214
7.4 Earlyenergy:definition,clarityindex,
speechtransmissionindex 221
7.5 Reverberationandreverberance 229
7.6 Soundpressurelevel,strengthfactor 238
7.7 Spaciousnessofsoundfields 239
7.8 Assessmentofconcerthallacoustics 242
References 248
8 Measuring techniques in room acoustics 251
8.1 Generalremarksoninstrumentation 252
8.2 Measurementoftheimpulseresponse 255
8.3 Examinationoftheimpulseresponse 261
8.4 Measurementofreverberation 268
8.5 Diffusion 273
8.6 Soundabsorption—tubemethods 279
8.7 Soundabsorption—reverberationchamber 284
8.8 Scatteringcoefficient 289
References 292
9 Design considerations and design procedures 294
9.1 Directsound 295
9.2 Examinationoftheroomshape 298
9.3 Reverberationtime 304
9.4 Predictionofnoiselevel 311
9.5 Acousticalscalemodels 316
9.6 Computersimulation 318
9.7 Auralisation 326
References 329
viii Contents
10 Electroacoustical systems in rooms 331
10.1 Loudspeakerdirectivity 332
10.2 Reachofaloudspeaker 337
10.3 Afewremarksonloudspeakerpositions 340
10.4 Acousticalfeedbackanditssuppression 345
10.5 Reverberationenhancementwithexternal
reverberators 351
10.6 Reverberationenhancementbycontrolled
feedback 358
References 363
List of symbols 365
Index 368
Preface to the fifth edition
I am delighted to present a new edition of my book Room Acoustics.
Preparing a new edition enabled me to take into consideration some new
publicationsinthefieldofroomacoustics.Furthermore,severalmorecon-
ventional subjects which were not incorporated into the earlier editions,
although being of great interest with regard to room acoustics, have been
included,alongwithsomenewfigures.Thechapteronmeasuringtechniques
has been restructured because of the rapid progress in signal processing.
Finally, the new edition has provided me with the opportunity to elimi-
nateanumberofincomplete,inaccurateorevenmisleadingformulationsor
expressionsandtoreplacethemwithmoreadequateones.
Despite all these modifications and additions, the original translation by
Professor Peter Lord, to whom I owe my sincere gratitude, is still the basis
of this text. Once more, I would like to thank the publisher for giving me
theopportunitytopresentarevisedversionofmywork,aswellasfortheir
excellentcooperation.
HeinrichKuttruff
Aachen