Noise Reduction in Speech Processing

by Benesty, Jacob; Chen, Jingdong; Huang, Yiteng; Cohen, Israel

• ISBN13: 9783642002953
• ISBN10: 3642002951
• Format: Hardcover
• Copyright: 2009-05-01
• Publisher: Springer Verlag

Summary

Noise is everywhere and in most applications that are related to audio and speech, such as human-machine interfaces, hands-free communications, voice over IP (VoIP), hearing aids, teleconferencing/telepresence/telecollaboration systems, and so many others, the signal of interest (usually speech) that is picked up by a microphone is generally contaminated by noise. As a result, the microphone signal has to be cleaned up with digital signal processing tools before it is stored, analyzed, transmitted, or played out. This cleaning process is often called noise reduction and this topic has attracted a considerable amount of research and engineering attention for several decades. One of the objectives of this book is to present in a common framework an overview of the state of the art of noise reduction algorithms in the single-channel (one microphone) case. The focus is on the most useful approaches, i.e., filtering techniques (in different domains) and spectral enhancement methods. The other objective of Noise Reduction in Speech Processing is to derive all these well-known techniques in a rigorous way and prove many fundamental and intuitive results often taken for granted. This book is especially written for graduate students and research engineers who work on noise reduction for speech and audio applications and want to understand the subtle mechanisms behind each approach. Many new and interesting concepts are presented in this text that we hope the readers will find useful and inspiring.

Table of Contents

Introduction	p. 1
Noise Reduction in Speech Processing	p. 1
The Paradigm for Noise Reduction	p. 6
A Brief History of Noise Reduction Research	p. 7
Organization of the Book	p. 10
Some Notes to the Reader	p. 13
Problem Formulation	p. 15
In the Time Domain	p. 15
In the Frequency Domain	p. 16
In the Karhunen-Loeve Expansion (KLE) Domain	p. 18
Summary	p. 20
Performance Measures	p. 21
Signal-to-Noise Ratio	p. 21
Noise-Reduction Factor	p. 24
Speech-Distortion Index	p. 25
Speech-Reduction Factor	p. 27
Discussion	p. 28
Mean-Squared Error Criterion	p. 31
In the Time Domain	p. 31
In the Frequency Domain	p. 32
In the KLE Domain	p. 34
Summary	p. 36
Pearson Correlation Coefficient	p. 37
Correlation Coefficient Between Two Random Variables	p. 37
Correlation Coefficient Between Two Random Vectors	p. 38
Frequency-Domain Versions	p. 39
KLE-Domain Versions	p. 39
Summary	p. 40
Fundamental Properties	p. 41
In the Time Domain	p. 41
In the Frequency Domain	p. 46
In the KLE Domain	p. 50
Summary	p. 57
Optimal Filters in the Time Domain	p. 59
Wiener Filter	p. 59
Tradeoff Filters	p. 64
Subspace Approach	p. 67
Experiments	p. 68
Experimental Setup	p. 68
Effect of Forgetting Factor on Performance	p. 70
Effect of Filter Length on Performance	p. 72
Performance in Different Noise Conditions	p. 74
Summary	p. 75
Optimal Filters in the Frequency Domain	p. 77
Wiener Filter	p. 77
Parametric Wiener Filter	p. 81
Tradeoff Filter	p. 82
Experiments	p. 86
Impact of Input SNR on Filter Gain and Speech Distortion	p. 86
Noise Estimation	p. 86
Performance Comparison in NYSE Noise	p. 89
Performance Comparison in Car Noise	p. 93
Summary	p. 94
Optimal Filters in the KLE Domain	p. 95
Class I	p. 95
Wiener Filter	p. 95
Parametric Wiener Filter	p. 100
Tradeoff Filter	p. 101
Class II	p. 105
Wiener Filter	p. 105
Tradeoff Filter	p. 108
Experiments	p. 111
Impact of Forgetting Factor on Performance of Class-I Filters	p. 111
Effect of Filter Length on Performance of Class-I Filters	p. 113
Estimation of Clean Speech Correlation Matrix	p. 114
Performance of Class-I Filters in Different Noise Conditions	p. 116
Impact of Forgetting Factor on Performance of Class-II Filters	p. 116
Effect of Filter Length on Performance of Class-II Filters	p. 120
Summary	p. 121
Optimal Filters in the Transform Domain	p. 123
Generalization of the KLE	p. 123
Performance Measures	p. 127
SNR	p. 127
Noise-Reduction Factor	p. 128
Speech-Distortion Index	p. 129
Speech-Reduction Factor	p. 130
MSE Criterion	p. 131
PCC and Fundamental Properties	p. 132
Examples of Filter Design	p. 138
Wiener Filter	p. 138
Parametric Wiener Filter	p. 142
Tradeoff Filter	p. 143
Examples of Unitary Matrices	p. 145
Experiments	p. 146
Performance of Wiener Filter in White Gaussian Noise	p. 146
Effect of Filter Length on Performance	p. 148
Performance of Tradeoff Filter in White Gaussian Noise	p. 148
Summary	p. 152
Spectral Enhancement Methods	p. 153
Problem Formulation	p. 153
Performance Measures	p. 155
SNR	p. 155
Noise-Reduction Factor	p. 156
Speech-Distortion Index	p. 157
Speech-Reduction Factor	p. 158
MSE Criterion	p. 159
Signal Model	p. 161
Signal Estimation	p. 162
MMSE Spectral Estimation	p. 162
MMSE Spectral Amplitude Estimation	p. 163
MMSE Log-Spectral Amplitude Estimation	p. 164
Spectral Variance Model	p. 166
GARCH Model	p. 166
Modeling Speech Spectral Variance	p. 168
Model Estimation	p. 169
Spectral Variance Estimation	p. 170
Relation to Decision-Directed Estimation	p. 172
Summary of Spectral Enhancement Algorithm	p. 174
Experimental Results	p. 176
Summary	p. 181
A Practical Example: Multichannel Noise Reduction for Voice Communication in Spacesuits	p. 183
Problem Description	p. 183
Problem Analysis	p. 186
Sources of Noise in Spacesuits	p. 186
Noise Cancelling Microphones	p. 188
Suggested Algorithms	p. 192
Nearfield, Wideband Microphone Array Beamforming for Speech Acquisition in Spacesuits	p. 193
Multichannel Noise Reduction: a More Practical Microphone Array Signal Processing Technique	p. 200
Single-Channel Noise Reduction	p. 201
Adaptive Noise Cancellation	p. 202
Algorithm Validation	p. 203
In-Helmet Multichannel Acoustic Data Collection	p. 203
Performance Evaluation of Beamforming Algorithms	p. 208
Validation of Multichannel Noise Reduction Algorithms	p. 214
Validation of Single-Channel Noise Reduction Algorithms	p. 214
Feasibility Assessment of Using Adaptive Noise Cancellation in Spacesuits	p. 214
Summary	p. 217
References	p. 219
Index	p. 227
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