Acoustics and Psychoacoustics, Second Edition (Music Technology)

Contents......Page 6
Series introduction......Page 8
Preface to the second edition......Page 10
1.1.1 The nature of sound waves......Page 12
1.1.2 The velocity of sound waves......Page 14
1.1.3 The velocity of sound in air......Page 16
1.1.4 The velocity of transverse waves......Page 18
1.1.5 The wavelength and frequency of sound waves......Page 20
1.1.6 The relationship between pressure, velocity and impedance in sound waves......Page 23
1.2 Sound intensity, power and pressure level......Page 25
1.2.1 Sound intensity level......Page 26
1.2.2 Sound power level......Page 27
1.2.3 Sound pressure level......Page 28
1.3 Adding sounds together......Page 31
1.3.1 The level when correlated sounds add......Page 32
1.3.2 The level when uncorrelated sounds add......Page 35
1.3.3 Adding decibels together......Page 36
1.4 The inverse square law......Page 39
1.4.1 The effect of boundaries......Page 42
1.5.2 Sound refraction......Page 44
1.5.4 Sound reflection from hard boundaries......Page 48
1.5.5 Sound reflection from bounded to unbounded boundaries......Page 49
1.5.6 Sound interference......Page 51
1.5.7 Standing waves at hard boundaries......Page 54
1.5.8 Standing waves at other boundaries......Page 56
1.5.9 Sound diffraction......Page 59
1.5.10 Sound scattering......Page 61
1.6.1 The spectrum of periodic sound waves......Page 62
1.6.3 The spectrum of non-periodic sound waves......Page 65
1.7 Analysing spectra......Page 67
1.7.1 Filters and filter types......Page 68
1.7.2 Filter time responses......Page 69
1.7.3 Time responses of acoustic systems......Page 71
1.7.4 Time and frequency representations of sounds......Page 73
References 1......Page 75
2 Introduction to hearing......Page 76
2.1.1 Outer ear function......Page 77
2.1.2 Middle ear function......Page 78
2.1.3 Inner ear function......Page 82
2.2 Critical bands......Page 85
2.3 Frequency and pressure sensitivity ranges......Page 90
2.4 Loudness perception......Page 93
2.4.1 Measuring loudness......Page 96
2.4.2 Loudness of simple sounds......Page 97
2.4.3 Loudness of complex sounds......Page 100
2.5 Noise-induced hearing loss......Page 102
2.5.1 Integrated noise dose......Page 105
2.5.2 Protecting your hearing......Page 106
2.6 Perception of sound source direction......Page 107
2.6.1 Interaural time difference (ITD)......Page 108
2.6.2 Interaural intensity difference (IID)......Page 112
2.6.3 Pinnae and head movement effects......Page 113
2.6.4 ITD and IID trading......Page 114
2.6.5 The Haas effect......Page 115
2.6.6 Stereophonic listening......Page 116
References 2......Page 119
3.1.1 Musical notes and their fundamental frequency......Page 120
3.1.2 Musical notes and their harmonics......Page 122
3.1.3 Musical intervals between harmonics......Page 125
3.2 Hearing pitch......Page 130
3.2.1 Place theory of pitch perception......Page 131
3.2.2 Problems with the place theory......Page 135
3.2.3 Temporal theory of pitch perception......Page 139
3.2.5 Contemporary theory of pitch perception......Page 144
3.2.6 Secondary aspects of pitch perception......Page 145
3.3 Hearing notes......Page 147
3.3.1 Harmonics and the development of Western harmony......Page 148
3.3.2 Consonance and dissonance......Page 149
3.3.3 Hearing musical intervals......Page 150
3.4 Tuning systems......Page 155
3.4.1 Pythagorean tuning......Page 156
3.4.2 Just tuning......Page 158
3.4.3 Equal tempered tuning......Page 160
References 3......Page 162
4.1 A 'black box' model of musical instruments......Page 163
4.2 Stringed instruments......Page 166
4.2.1 Sound source from a plucked string......Page 168
4.2.2 Sound source from a struck string......Page 169
4.2.3 Sound source from a bowed string......Page 171
4.2.4 Sound modifiers in stringed instruments......Page 173
4.3.1 Sound source in organ flue pipes......Page 177
4.3.2 Sound modifiers in organ flue pipes......Page 181
4.3.3 Woodwind flue instruments......Page 188
4.3.4 Sound source in organ reed pipes......Page 191
4.3.5 Sound modifiers in organ reed pipes......Page 193
4.3.6 Woodwind reed instruments......Page 194
4.3.7 Brass instruments......Page 200
4.4 Percussion instruments......Page 205
4.4.2 Sound modifiers in percussion instruments......Page 206
4.5 The speaking and singing voice......Page 209
4.5.1 Sound source in singing......Page 210
4.5.2 Sound modifiers in singing......Page 213
References 4......Page 219
5.1 What is timbre?......Page 221
5.2 Acoustics of timbre......Page 222
5.2.1 Note envelope......Page 225
5.2.2 Note onset......Page 226
5.3 Psychoacoustics of timbre......Page 231
5.3.1 Critical bands and timbre......Page 232
5.3.2 Acoustic cues and timbre perception......Page 234
5.4 The pipe organ as a timbral synthesiser......Page 237
5.5.1 Perception of pure tones......Page 239
5.5.2 Masking of one sound by another......Page 241
5.5.3 Note grouping illusions......Page 247
5.5.4 Pitch illusions......Page 253
References 5......Page 257
6.1.1 The direct sound......Page 258
6.1.2 Early reflections......Page 260
6.1.3 The effect of absorption on early reflections......Page 264
6.1.4 The reverberant sound......Page 265
6.1.5 The behaviour of the reverberant sound field......Page 267
6.1.6 The balance of reverberant to direct sound......Page 268
6.1.7 The level of the reverberant sound in the steady state......Page 269
6.1.8 Calculating the critical distance......Page 273
6.1.9 The effect of source directivity on the reverberant sound......Page 275
6.1.11 Calculating and predicting reverberation time......Page 278
6.1.12 The effect of room size on reverberation time......Page 280
6.1.14 A simpler reverberation time equation......Page 282
6.1.15 Reverberation faults......Page 283
6.1.16 Reverberation time variation with frequency......Page 286
6.1.17 Reverberation time calculation with mixed surfaces......Page 287
6.1.18 Reverberation time design......Page 290
6.1.19 Ideal reverberation time characteristics......Page 293
6.1.20 Early decay time......Page 294
6.1.21 Lateral reflections......Page 295
6.1.22 Early reflections and performer support......Page 296
6.1.23 The effect of air absorption......Page 298
6.2 Room modes and standing waves......Page 299
6.2.1 Axial modes......Page 301
6.2.2 Tangential modes......Page 302
6.2.4 A universal modal frequency equation......Page 303
6.2.5 The Bonello criteria......Page 304
6.2.7 The decay time of axial modes......Page 306
6.2.8 The decay time of other mode types......Page 307
6.2.9 Critical frequency......Page 311
6.2.11 Calculating the critical frequency......Page 313
6.3.1 Porous absorbers......Page 316
6.3.2 Resonant absorbers......Page 318
6.3.3 Helmholtz absorbers......Page 319
6.3.4 Wideband absorbers......Page 320
6.3.5 Summary......Page 321
6.4.1 How diffusers work......Page 322
6.4.3 Amplitude reflection gratings......Page 325
6.5 Sound isolation......Page 327
6.5.1 Ways of achieving sound isolation......Page 328
6.5.2 Independent partitions......Page 330
6.5.3 Flanking paths......Page 331
6.6 Energy-time considerations......Page 332
6.6.1 Reflection-free zones......Page 333
6.6.2 Absorption level required for reflection-free zones......Page 335
References 6......Page 336
7.1 Filtering......Page 338
7.2 Equalisation and tone controls......Page 342
7.2.1 Correcting frequency response faults due to the recording process......Page 343
7.2.3 Altering the balance of sounds in mixes......Page 344
7.3.1 Analogue reverberation techniques......Page 346
7.3.2 Digital reverberation techniques......Page 348
7.4 Chorus, automatic double tracking (ADT), phasing and flanging effects......Page 354
7.5 Pitch processing and time modification......Page 358
7.6 Sound morphing and vocoding......Page 365
7.7.2 Dolby Stereo......Page 367
7.7.3 Ambisonics......Page 368
7.7.4 Binaural stereo......Page 370
7.8 Loudness processing......Page 372
References 7......Page 375
Appendix 1: Solving the ERB equation......Page 378
Appendix 2: Converting between frequency ratios and cents......Page 380
Appendix 3: Deriving the reverberation time equation......Page 382
Appendix 4: Deriving the reverberation time equation for different frequencies and surfaces......Page 386
Index......Page 390