Parametric Time-Frequency Domain Spatial Audio

A comprehensive guide that addresses the theory and practice of spatial audio

This book provides readers with the principles and best practices in spatial audio signal processing. It describes how sound fields and their perceptual attributes are captured and analyzed within the time-frequency domain, how essential representation parameters are coded, and how such signals are efficiently reproduced for practical applications. The book is split into four parts starting with an overview of the fundamentals. It then goes on to explain the reproduction of spatial sound before offering an examination of signal-dependent spatial filtering. The book finishes with coverage of both current and future applications and the direction that spatial audio research is heading in.

Parametric Time-frequency Domain Spatial Audio focuses on applications in entertainment audio, including music, home cinema, and gaming--covering the capturing and reproduction of spatial sound as well as its generation, transduction, representation, transmission, and perception. This book will teach readers the tools needed for such processing, and provides an overview to existing research. It also shows recent up-to-date projects and commercial applications built on top of the systems.

• Provides an in-depth presentation of the principles, past developments, state-of-the-art methods, and future research directions of spatial audio technologies

• Includes contributions from leading researchers in the field

• Offers MATLAB codes with selected chapters

An advanced book aimed at readers who are capable of digesting mathematical expressions about digital signal processing and sound field analysis, Parametric Time-frequency Domain Spatial Audio is best suited for researchers in academia and in the audio industry.

Autorentext

VILLE PULKKI, PHD, is an Associate Professor leading the Communication Acoustics Research Group in the Department of Signal Processing and Acoustics, Aalto University, Finland. He has received distinguished medal awards from Society of Motion Picture and Television Engineers and from Audio Engineering Society. SYMEON DELIKARIS-MANIAS is a postdoc researcher affiliated with the Communication Acoustics Research Group in the Department of Signal Processing and Acoustics at Aalto University, Finland. ARCHONTIS POLITIS, PHD, is a postdoc researcher affiliated with the Communication Acoustics Research Group in the Department of Signal Processing and Acoustics at Aalto University and Tampere University of Technology in Finland.

Inhalt
Contents

List of Contributors xiii

Preface xv

About the Companion Website xix

Part I Analysis and Synthesis of Spatial Sound 1

TimeFrequency Processing: Methods and Tools 3
Juha Vilkamo and Tom Ba¨ckstro¨m

1.1 Introduction 3

1.2 TimeFrequency Processing 4

1.2.1 Basic Structure 4

1.2.2 Uniform Filter Banks 5

1.2.3 Prototype Filters and Modulation 6

1.2.4 A Robust Complex-Modulated Filter Bank, and Comparison with STFT 8

1.2.5 Overlap-Add and Windowing 12

1.2.6 Example Implementation of a Robust Filter Bank in Matlab 13

1.2.7 Cascaded Filters 15

1.3 Processing of Spatial Audio 16

1.3.1 Stochastic Estimates 17

1.3.2 Decorrelation 18

1.3.3 Optimal and Generalized Solution for Spatial Sound Processing Using Covariance Matrices 19

References 23

**2 Spatial Decomposition by Spherical Array Processing 25
**David Lou Alon and Boaz Rafaely

2.1 Introduction 25

2.2 Sound Field Measurement by a Spherical Array 26

2.3 Array Processing and Plane-Wave Decomposition 26

2.4 Sensitivity to Noise and Standard Regularization Methods 29

2.5 Optimal Noise-Robust Design 32

2.5.1 PWD Estimation Error Measure 32

2.5.2 PWD Error Minimization 34

2.5.3 R-PWD Simulation Study 35

2.6 Spatial Aliasing and High Frequency Performance Limit 37

2.7 High Frequency Bandwidth Extension by Aliasing Cancellation 39

2.7.1 Spatial Aliasing Error 39

2.7.2 AC-PWD Simulation Study 40

2.8 High Performance Broadband PWD Example 42

2.8.1 Broadband Measurement Model 42

2.8.2 Minimizing Broadband PWD Error 42

2.8.3 BB-PWD Simulation Study 44

2.9 Summary 45

2.10 Acknowledgment 46

References 46

**3 Sound Field Analysis Using Sparse Recovery 49
**Craig T. Jin, Nicolas Epain, and Tahereh Noohi

3.1 Introduction 49

3.2 The Plane-Wave Decomposition Problem 50

3.2.1 Sparse Plane-Wave Decomposition 51

3.2.2 The Iteratively Reweighted Least-Squares Algorithm 51

3.3 Bayesian Approach to Plane-Wave Decomposition 53

3.4 Calculating the IRLS Noise-Power Regularization Parameter 55

3.4.1 Estimation of the Relative Noise Power 56

3.5 Numerical Simulations 58

3.6 Experiment: Echoic Sound Scene Analysis 59

3.7 Conclusions 65

Appendix 65

References 66

Part II Reproduction of Spatial Sound 69

Overview of TimeFrequency Domain Parametric Spatial Audio Techniques 71
Archontis Politis, Symeon Delikaris-Manias, and Ville Pulkki

4.1 Introduction 71

4.2 Parametric Processing Overview 73

4.2.1 Analysis Principles 74

4.2.2 Synthesis Principles 75

4.2.3 Spatial Audio Coding and Up-Mixing 76

4.2.4 Spatial Sound Recording and Reproduction 78

4.2.5 Auralization of Measured Room Acoustics and Spatial Rendering of Room Impulse Responses 81

References 82

**5 First-Order Directional Audio Coding (DirAC) 89
**Ville Pulkki, Archontis Politis, Mikko-Ville Laitinen, Juha Vilkamo, and Jukka Ahonen

5.1 Representing Spatial Sound with First-Order B-Format Signals 89

5.2 Some Notes on the Evolution of the Technique 92

5.3 DirAC with Ideal B-Format Signals 94

5.4 Analysis of Directional Parameters with Real Microphone Setups 97

5.4.1 DOA Analysis with Open 2D Microphone Arrays 97

5.4.2 DOA Analysis with 2D Arrays with a Rigid Baffle 99

5.4.3 DOA Analysis in Underdetermined Cases 101

5.4.4 DOA Analysis: Further Methods 102

5.4.5 Effect of Spatial Aliasing and Microphone Noise on the Analysis of Diffuseness 103

5.5 First-Order DirAC with Monophonic Audio Transmission 105 5.6 First-O...