Measurements in Room Acoustics : : Uncertainties and Influence of the Measurement Position / / Ingo B. Witew.

• Superior document: Aachener Beiträge zur Akustik
• VerfasserIn: Witew, Ingo B.,
• Place / Publishing House: Berlin, Germany : : Logos Verlag Berlin GmbH,, 2022.
• Year of Publication: 2022
• Language: English
• Series: Aachener Beiträge zur Akustik.
• Physical Description: 1 online resource (292 pages)

Regardless of the field, measurements are essential for validating theories and making well-founded decisions. A criterion for the validity and comparability of measured values is their uncertainty. Still, in room acoustical measurements, the application of established rules to interpret uncertainti...

Table of Contents

• 1 Introduction 1
• 1.1 Defining the scope of this work . 4
• 2 Fundamentals and previous work 5
• 2.1 Theoretical principles behind spatial fluctuations . 5
• 2.1.1 Amplitude distribution due to changes in position 5
• 2.1.2 The impulse response and other room acoustical quantities 10
• 2.1.3 Variance of the reverberation time over space . 13
• 2.1.4 Reference to the research question . 14
• 2.2 Acoustical measurements in auditoria . 15
• 2.2.1 Principles and established practice . 15
• 2.2.2 Measurement uncertainty in architectural acoustics 18
• 2.2.3 Observations in other fields of acoustics 21
• 2.3 Uncertainties in measurements . 23
• 2.3.1 General metrological terms . 23
• 2.3.2 The guide to the expression of uncertainty
• in measurement 24
• 2.4 The perception of sound in auditoria 33
• 3 General Methodology 37
• 4 Uncertainty of room impulse response measurements 41
• 4.1 Introduction 41
• 4.2 Uncertainty budget for room impulse response measurements 42
• 4.3 Discussion . 45
• 4.4 Conclusions 45
• 5 Design of a measurement array 47
• 5.1 Introduction 47
• 5.2 Methodology . 48
• 5.2.1 Requirements for the measurement setup . 48
• 5.2.2 Design of a measurement device 52
• 5.2.3 Acoustical measurements 53
• 5.2.4 Data analysis . 56
• 5.3 Results . 57
• 5.3.1 Visualization of sound fields . 57
• 5.3.2 Data for the uncertainty discussions 60
• 5.4 Discussion . 60
• 5.5 Conclusions 62
• 6 Uncertain input quantities of the measurement function 65
• 6.1 Introduction 65
• 6.2 Uncertainty of room acoustical quantities . 66
• 6.2.1 Methodology . 66
• 6.2.2 Results 74
• 6.3 Uncertainty of the sampling location 82
• 6.3.1 Introduction . 82
• 6.3.2 Initial methodology . 84
• 6.3.3 Results 87
• 6.3.4 Revised methodology . 88
• 6.3.5 Results 88
• 6.4 Discussion . 90
• 6.5 Conclusions 91
• 7 Measurement function 93
• 7.1 Introduction 93
• 7.2 Establishing the measurement function . 94
• 7.2.1 Methodology . 94
• 7.2.2 Results and discussion 99
• 7.3 Compensating the effect of a finite sampling area . 103
• 7.3.1 Methodology . 103
• 7.3.2 Results and discussion 104
• 7.4 Reducing the complexity . 106
• 7.4.1 Methodology . 106
• 7.4.2 Results 107
• 7.5 Discussion . 108
• 7.6 Conclusions 110
• 8 Validity of the measurement function 111
• 8.1 Introduction 111
• 8.2 Methodology . 111
• 8.2.1 Repeatability . 112
• 8.2.2 Reproducibility 112
• 8.3 Results . 117
• 8.3.1 Repeatability . 119
• 8.3.2 Reproducibility 121
• 8.4 Discussion . 139
• 8.5 Conclusions 141
• 9 How accurately must a measurement position be defined? 143
• 9.1 Introduction 143
• 9.2 Methodology . 144
• 9.2.1 Establishing the input quantity distribution 145
• 9.2.2 Implementing the measurement function 147
• 9.2.3 Determining the measurement uncertainty using Monte
• Carlo simulations . 148
• 9.3 Results . 150
• 9.3.1 Uncertainty of room acoustical quantities . 151
• 9.3.2 Effect of the auditorium's reverberation 156
• 9.3.3 Effect of the evaluation interval (time) . 159
• 9.3.4 Effect of the center frequency 162
• 9.3.5 Effect of the bandwidth . 164
• 9.4 Discussion . 166
• 9.4.1 Uncertainty of broadband measurements 166
• 9.4.2 Reference to theory . 168
• 9.4.3 Appropriateness of regression models 173
• 9.4.4 Influence of early reflections . 174
• 9.4.5 Necessity for measurements . 175
• 9.5 Conclusions 175
• 10 General results 179
• 10.1 Uncertainty of measured impulse responses 179
• 10.2 Uncertainty of room acoustical quantities . 180
• 10.3 Uncertainty due to spatial fluctuations . 181
• 11 General Discussion 187
• 11.1 Uncertainty of measured impulse responses 188
• 11.2 Uncertainty of room acoustical quantities . 189
• 11.3 Uncertainty due to spatial fluctuations . 190
• 11.4 Critical aspects 191
• 11.5 Implications 192
• 12 General conclusions and outlook 195
• 12.1 General conclusions 195
• 12.2 Outlook 196
• 13 Acknowledgements 199
• Bibliography 201
• A Detailed discussion of uncertainties in
• room impulse response measurements 215
• A.1 Introduction 215
• A.2 Formulation stage 215
• A.2.1 The output quantity . 215
• A.2.2 The input quantities . 216
• A.2.3 The measurement model . 219
• A.3 Results - Calculation stage 260
• A.4 Discussion . 263
• A.5 Conclusions 265
• B Influence of the measurement apparatus on the sound field 267
• B.1 Introduction 267
• B.2 Analytical approach . 268
• B.2.1 Methodology . 268
• B.2.2 Results 270
• B.3 Empirical approaches . 275
• B.3.1 Methodology . 275
• B.3.2 Results 277
• B.4 Discussion . 279
• B.5 Conclusions 281
• C Uncertainty propagation for room acoustical quantities 283
• C.1 Energy decay curve 283
• C.2 Reverberation times . 285
• C.3 Clarity.