AUDIO SIGNAL PROCESSING FOR NEXT- GENERATION MULTIMEDIA COMMUNI CATION SYSTEMS

Transcription

1 AUDIO SIGNAL PROCESSING FOR NEXT- GENERATION MULTIMEDIA COMMUNI CATION SYSTEMS Edited by YITENG (ARDEN) HUANG Bell Laboratories, Lucent Technologies JACOB BENESTY Universite du Quebec, INRS-EMT Kluwer Academic Publishers Boston/Dordrecht/London

2 Contents Preface xi Contributing Authors 1 Introduction 1 Yiteng (Arden) Huang Jacob Benesty 1. Multimedia Communications 1 2. Challenges and Opportunities 3 3. Organization of the Book 4 xiii Part I Speech Acquisition and Enhancement 2 Differer itial Microphone Arrays Gary W. Elko Introduction Differential Microphone Arrays Array Directional Gain Optimal Arrays for Isotropic Fields 4.1 Maximum Directional Gain 4.2 Maximum Directivity Index for Differential Microphones 4.3 Maximum Front-to-Back Ratio 4.4 Minimum Peak Directional Response 4.5 Beamwidth Design Examples 5.1 First-Order Designs 5.2 Second-Order Designs 5.3 Third-Order Designs 5.4 Higher-Order designs Sensitivity to Microphone Mismatch and Noise Conclusions

3 vi Audio Signal Processing 3 Spherical Microphone Arrays for 3D Sound Recording 67 Jens Meyer Gary W. Elko 1. Introduction Fundamental Concept The Eigenbeamformer Discrete Orthonormality The Eigenbeams The Modal Coefficients Modal-Beamformer Combining Unit Steering Unit Robustness Measure Beampattern Design Arbitrary Beampattern Design Optimum Beampattern Design Measurements Summary Appendix A 89 4 Subband Noise Reduction Methods for Speech Enhancement 91 Eric J. Diethorn 1. Introduction Wiener Filtering Speech Enhancement by Short-Time Spectral Modification Short-Time Fourier Analysis and Synthesis Short-Time Wiener Filter Power Subtraction Magnitude Subtraction Parametric Wiener Filtering Review and Discussion Averaging Techniques for Envelope Estimation Moving Average Single-Pole Recursion Two-Sided Single-Pole Recursion Nonlinear Data Processing Example Implementation Subband Filter Bank Architecture A-Posteriori-SNR Voice Activity Detector Example Conclusion 111 Part II Acoustic Echo Cancellation 5 Adaptive Algorithms for MIMO Acoustic Echo Cancellation 119 Jacob Benesty Tomas Gänsler Yiteng (Arden) Huang Markus Rupp 1. Introduction Normal Equations and Identification of a MIMO System Normal Equations 121

4 Contents Vll 2.2 The Nonuniqueness Problem The Impulse Response Tail Effect Some Different Solutions for Decorrelation The Classical and Factorized Multichannel RLS The Multichannel Fast RLS The Multichannel LMS Algorithm Classical Derivation Improved Version The Multichannel APA The Straightforward Multichannel APA The Improved Two-Channel APA The Improved Multichannel APA The Multichannel Exponentiated Gradient Algorithm The Multichannel Frequency-domain Adaptive Algorithm Conclusions Double-Talk Detectors for Acoustic Echo Cancelers 149 Tomas Gänsler Jacob Benesty 1. Introduction Basics of AEC and DTD AEC Notations The Generic DTD A Suggestion to Performance Evaluation of DTDs Double-Talk Detection Algorithms The Geigel Algorithm The Cross-Correlation Method The Normalized Cross-Correlation Method The Coherence Method The Normalized Cross-correlation Matrix The Two-Path Model DTD Combinations with Robust Statistics Comparison of DTDs by Means of the ROC Discussion The WinEC: A Real-Time Hands-Free Stereo Communication System 171 Tomas Gänsler Volker Fischer Eric J. Diethorn Jacob Benesty 1. Introduction 1.1 Signal model System Description The Audio Module The Network Module The Echo Canceler Module Algorithms of the Echo Canceler Module Adaptive Filter Algorithm Residual Echo and Noise Suppression Masking Threshold for Residual Echo in Noise Analysis of Echo Suppression Requirements Noise and Residual Echo Suppression Simulations Real-Time Tests with Different Modes of Operation 189

5 viii Audio Signal Processing 6.1 Point-to-Point Communication Multi-Point Communication Transatlantic Teleconference in Stereo Discussion 191 Part IH Sound Source Tracking and Separation 8 Time Delay Estimation 197 Jingdong Chen Yiteng (Arden) Huang Jacob Benesty 1. Introduction Signal Models Ideal Propagation Model Multipath Model Reverberant Model Generalized Cross-Correlation Method The Multichannel Cross-Correlation Algorithm Spatial Prediction Technique Time Delay Estimation Using Spatial Prediction Other Information from the Spatial Correlation Matrix Adaptive Eigenvalue Decomposition Algorithm Adaptive Multichannel Time Delay Estimation Principle Time-Domain Multichannel LMS Approach Frequency-Domain Adaptive Algorithms Experiments Experimental Setup Performance Measure Experimental Results Conclusions Source Localization 229 Yiteng (Arden) Huang Jacob Benesty Gary W. Elko 1. Introduction Source Localization Problem Measurement Model and Cramer-Rao Lower Bound for Source Localization Maximum Likelihood Estimator Least Squares Estimators The Least Squares Error Criteria Spherical Intersection (SX) Estimator Spherical Interpolation (SI) Estimator Linear-Correction Least Squares Estimator Example System Implementation Source Localization Examples Conclusions Blind Source Separation for Convolutive Mixtures: A Unified Treatment 255 Herbert Büchner Robert Aichner Walter Kellermann

6 Contents ix 1. Introduction Generic Block Time-Domain BSS Algorithm Matrix Notation for Convolutive Mixtures Cost Function and Algorithm Derivation Equivariance Property and Natural Gradient Special Cases and Links to Known Time-Domain Algorithms Generic Frequency-Domain BSS Algorithm General Frequency-Domain Formulation Natural Gradient in the Frequency Domain Special Cases and Links to Known Frequency-Domain Algorithms Weighting Function Off-line Implementation On-line Implementation В lock-on-line Implementation Part IV 11 Audio Coding Gerald Schüler Experiments and Results Conclusions Audio Coding and Realistic Soun Introduction Psycho-Acoustics Filter Banks 3.1 Polyphase Formulation 3.2 Modulated Filter Banks 3.3 Block Switching Current and Basic Coder Structures Stereo Coding Low Delay Audio Coding Conclusions Sound Field Synthesis 323 Sascha Spors Heinz Teutsch Achim Kuntz Rudolf Rabenstein 1. Introduction Rendering of Sound Fields with Wave Field Synthesis Physical Foundation of Wave Field Synthesis Wave Field Synthesis Based Sound Reproduction Model-based and Data-Based Rendering Data-Based Rendering Model-Based Rendering Hybrid Approach Wave Field Analysis Loudspeaker and Listening Room Compensation Listening Room Compensation Loudspeaker Compensation Description of a Sound Field Transmission System 339

7 X Audio Signal Processing 6.1 Acquisition of Source Signals Sound Stage Reproduction Using Wave Field Synthesis Summary Virtual Spatial Sound 345 Carlos Avendano 1. Introduction 1.1 Scope Spatial Hearing Interaural Coordinate System Interaural Differences Spectral Cues Distance Cues Dynamic Cues Acoustics of Spatial Sound TheHRTF Room Acoustics Virtual Spatial Sound Systems HRTF Measurement HRTF Modelling Virtual Spatial Sound Rendering Conclusions 366 Index 371