The Art and Science of 3D Audio Recording

Preface
Contents
About the Author
Abbreviations
1 Introductory Critical Analysis and Case Studies
1.1 Diffuse Field Image Predictor (DFI) and Signal Correlation in Stereo and Surround Systems
1.2 Qualitative Considerations Concerning Ambisonics
1.3 Surround Microphone Case Study: OCT-Surround
1.4 Naturalness and Related Aspects in the Perception of Reproduced Music
1.5 Inter Aural Cross-Correlation (IACC) and the Binaural Quality Index of Reproduced Music (BQIrep)
1.6 Case Study: Intercapsule Signal Correlation in a Hamasaki Square
1.7 Some Thoughts on Psychoacoustic Signal Interaction in Multichannel Microphone Array Systems
1.8 A Few Thoughts on Microphone Pattern Choice and Capsule Orientation in 3D Audio
1.9 Some Thoughts on Time-Alignment in 3D Microphone Array Systems
1.10 Distribution of Direct- and Diffuse-Sound Reproduction in Multichannel Loudspeaker Systems
1.11 Some Thoughts on Optimized Loudspeaker Directivity
1.12 Conclusion
References
2 ‘3D’- or ‘Immersive’ Audio—The Basics and a Primer on Spatial Hearing
2.1 Influence of Listening Environment and Subjective Evaluation of 3D, Surround and Stereo Loudspeaker Reproductions
2.2 Basics of Sound Perception in Humans
2.3 Mechanisms of Localization
2.3.1 HRTF Phase-Characteristics
2.3.2 Localization and HRTFs
2.4 Mechanisms of Distance Perception
2.4.1 Sound Intensity
2.4.2 Diffuse Sound
2.4.3 Frequency Response
2.4.4 Binaural Differences
2.5 Spatial Impression
2.6 Physical Measures in Relation to Spatial Impression
2.7 The Influence of Loudspeaker Quality and Listening Room Acoustics on Listener Preference
2.8 Psychoacoustic Effects Concerning Localization and Spatial Impression with Loudspeaker Reproduction
2.8.1 Frequency Dependent Localization-Distortion in the Horizontal Plane
2.8.2 Frequency-Dependent Localization in the Vertical Plane
2.8.3 Effects Concerning the Reproduction of Spaciousness
References
3 The ‘AURO-3D®’ System and Format
3.1 Historic Development of Auro-3D and Competitive Systems
3.2 Auro-3D—Basic Concept and System Description
3.2.1 Auro-3D Engine
3.2.2 A Vertically Coherent Soundfield
3.2.3 3D-Reflections Around Sound Objects
3.2.4 Efficiency as a Key Element
3.3 Auro-3D Listening Formats for Home, Music and Broadcast Applications
3.4 Room Acoustics and Practical Speaker Setup for Auro-3D
3.4.1 Auro-3D Screensound
3.4.2 Further Aspects in Relation to Room Acoustics and Practical Speaker Setup
3.4.3 Speaker Positioning and Time Alignment in Home Setups
3.4.4 Tilt of the Height Speakers
3.4.5 Multiple Top Speakers
3.4.6 Subwoofers
3.4.7 Bass Management
3.4.8 Polarity
3.4.9 Signal Delay
3.4.10 Room Equalization
3.5 Installs for Digital Cinema and Dubbing Stages
3.5.1 ‘AuroMax’—Concept and Speaker Layouts
3.6 Content Creation
3.6.1 Workflow Considerations
3.6.2 Auro-3D Music and Broadcast Production as a Linear Based Workflow
3.6.3 Post-production and Mixing for Auro-3D (X-Curve Based Workflow)
3.6.4 Auro-3D Stem Layout
3.6.5 Encoding and Authoring for Auro-3D
3.6.6 Covering the Auro-3D System with Only Eight Products
3.7 Practical Experience: Ronald Prent on ‘Recording and Mixing in Auro 3D’
3.8 Practical Experience: Darcy Proper on ‘Mastering in Auro-3D’
References
4 The DOLBY® “Atmos™” System
4.1 The Introduction of Digital Cinema
4.2 Dolby Atmos—An Overview
4.3 Multichannel Speaker-Layout: Improved Audio Quality and Timbre Matching
4.3.1 Top-Speaker Aiming
4.3.2 Spatial Control and Resolution
4.4 Objects and Metadata
4.5 Workflow Integration—In the Dubbing Theatre
4.5.1 Dolby Certification
4.5.2 Packaging
4.5.3 Distribution
4.5.4 In the Cinema
4.6 Audio Postproduction and Mastering
4.6.1 Production Sound
4.6.2 Editing and Premixing
4.6.3 Final Mixing
4.6.4 Mastering
4.6.5 Digital Cinema Packaging and Distribution Audio File Delivery
4.6.6 Track File Encryption
4.7 Practical Experience: John Johnson on the Process of Dolby Atmos Mixing
4.7.1 The Local Renderer
4.7.2 Monitor Control
4.7.3 Upmixing
4.7.4 The Future of Object-Based Audio
4.8 Dolby Atmos in Live-Sound Reinforcement and Mixing
4.9 Practical Experience: Iker Olabe on Music Production in Dolby Atmos
4.9.1 Context
4.9.2 Introduction and Software
4.9.3 Dolby Atmos Renderer (DAR)
4.9.4 Loudspeaker Monitoring and Routing
4.9.5 Dolby Atmos Music with Headphones
4.9.6 Binaural Render Mode
4.9.7 Dolby Atmos Personalized Rendering and PHRTF
4.9.8 Renderer Sources
4.9.9 Dolby Atmos Music Panner (DAMP)
References
5 HOA—Higher Order Ambisonics (Eigenmike®)
5.1 Theoretical Background
5.2 A Comparison Between HOA and Other Mic-Techniques for 3D Audio
5.2.1 Why is Stereo Different?
5.2.2 What is an Ambience Microphone?
5.2.3 One Recording Method for All 3D Formats?
5.2.4 Is First-Order Ambisonics Adequate for 3D?
5.2.5 Criteria for Stereophonic Arrays Used in Ambience Capture for 3D Audio
5.3 A Comparison Among Commercially Available Ambisonic and Other 3D Microphones
5.3.1 Sennheiser ‘Ambeo’
5.3.2 SoundField ‘MKV’
5.3.3 Core Sound ‘TetraMic’
5.3.4 mh Acoustics ‘Eigenmike’®
5.3.5 Zoom ‘H2n’
5.4 The ‘Eigenmike®’, Octomic and ZM-1
5.5 Practical Experience: Dennis Baxter on Higher Order Ambisonics for Broadcast Applications
5.5.1 Capture or Create?
References
6 The Isosceles-Triangle, M.A.G.I.C Array and MMAD 3D (After Williams)
6.1 The 1st Layer—The M.A.G.I.C. Array
6.2 The 2nd Layer—Addition of Height Information
6.2.1 The Reason for Choosing 52 cm Between the 2nd Layer Capsules
6.3 The Primary Isosceles Triangle Structure
6.4 Psychoacoustic Experiences with the M.A.G.I.C. System
6.5 The 7 Channel Listening Experience
6.6 The Listening Tests
6.7 Experiments in Vertical Localization and Mic-Array Proposals
6.7.1 The Psychoacoustic Parameters for Vertical Virtual Localization in the First 45° Segment of Elevation
6.7.2 The Psychoacoustic Parameters for Vertical Virtual Localization in the 45° Segment of Elevation from +45° to +90°
6.7.3 The “Witches Hat” Localization System
6.7.4 The “Top Hat” Localization System
6.7.5 “Integral 3D” Compatibility Tests
6.7.6 From “Integral 3D” to “Comfort 3D”
6.7.7 MMAD 3D Audio
6.8 Summary
References
7 DTS:X®
7.1 The History of DTS—Digital Theatre Systems
7.2 DTS:X® Immersive Audio Cinema Format
7.3 DTS:X Theatre Speaker Configuration Options
7.3.1 Base Layer
7.3.2 Height Layer
7.3.3 Base Layer Speaker Spacing Requirements
7.3.4 Height Speaker Position Requirements
7.3.5 Speaker Cluster Options
7.3.6 Overall System Bass Requirements
7.3.7 B-Chain Considerations
7.4 DTS:X Home Cinema Speaker Configuration Options
7.5 The DTS® Content Creator Software
7.6 DTS Renderer Input
7.7 DTS Monitor
7.8 DTS Headphone:X—Headphone Monitor
7.9 DTS Neural:X Upmixer
7.10 DTS:X® Encoder
7.11 DTS:X® Mediaplayer
7.12 DTS:X Bitstream Tools
References
8 SONY “360 Reality Audio”
8.1 Object- or Compact-View
8.2 Focus View
8.3 Available Loudspeaker Layouts
8.4 Practical Aspects of the 360 WalkMix Creator™
References
9 Recording Microphone Techniques for 3D-Audio
9.1 Music Recordings with Large Orchestra
9.2 Music Recording with Small Orchestra, Grand Piano Solo
9.3 Music Recording with String Quartet
9.4 Music Recording with Church-Organ
9.5 Music Recording with Soloist
9.6 The AB-BPT-3D System for Decorrelated Signal Recording
9.7 The Bowles Array with Height Layer
9.8 Ellis-Geiger Triangle
9.8.1 Front Sets
9.8.2 Rear Set
9.8.3 Ellis-Geiger Triangle to Auro-3D 9.1 Mapping
9.8.4 Ellis-Geiger Triangle Mapping for Dolby Atmos (8.1 + 4 × Height)
9.8.5 Ellis-Geiger Triangle and Height Speakers
9.9 The Geluso ‘MZ-Microphone’ Technique
9.9.1 Perception of Height Channels
9.9.2 Stereo Height Channels
9.9.3 With Height Systems Using Z Microphone Techniques
9.10 The Zhang-Geluso ‘3DCC’ Technique: A Native B-Format Approach to Recording
9.10.1 Dual –Capsule Technology
9.10.2 3DCC Configuration
9.10.3 Primary Signals
9.10.4 Secondary Signals
9.10.5 Practical Application of the 3DCC Microphone Array
9.10.6 Height Signal Reproduction
9.10.7 Conclusion
9.11 The Morton Lindberg “2L” Technique
9.11.1 Use of Center Speaker and LFE-Channel
9.11.2 Coincident and Ambisonic Versus Spaced AB
9.12 The OCT-3D Technique
9.13 The ORTF-3D Technique
9.13.1 Conversion of the ORTF-3D Setup for Dolby Atmos and Auro3D
9.14 The ‘Minotaur 3D Array’ (Olabe and Lagatta)
9.15 ‘6DOF’ Mic System for VR-Applications (Rivaz-Mendes et al.)
9.15.1 ‘6DOF’ Versus ‘3DOF’ Recording
9.15.2 Recording Setup
9.15.3 Recording Process
9.15.4 Rendering Approaches
9.15.5 Example Implementation
9.15.6 Conclusions
9.16 Binaurally Based 3D-Audio Approaches
References
10 Comparative 3D Audio Microphone Array Tests
10.1 The Luthar-Maltezos 9.1 Experiment (Decca vs. Fukada/OCT Tree)
10.1.1 Recording Methodology
10.1.2 Recording Reproduction and Playback
10.1.3 Choice of Microphone Polar Pattern in Relation to Program Material
10.1.4 Conclusions
10.2 Twins-Square Versus Double-MSZ—A Comparative Test
10.2.1 Spatial Audio Evaluation
10.2.2 Recording Conditions
10.2.3 Reproduction System
10.2.4 Conclusion
10.3 The “Howie 3D-Tree” Versus “Hamaski-3D” Versus “HOA” for 22.2 Orchestra Recording
10.3.1 Listening Test Conditions and Creation of the Stimuli
10.3.2 The Test Results
10.3.3 Overall Performance of Recording Techniques
10.3.4 Naturalness and Sound Source Envelopment
10.4 Comparison of 9-Channel 3D Recording for Solo Piano
10.4.1 Spaced Recording Techniques
10.4.2 Near-Coincident Recording Techniques
10.4.3 Coincident Recording Techniques
10.4.4 Objective Measures for Multichannel Audio Evaluation
10.4.5 The Recording Techniques Under Investigation
10.4.6 Subjective Evaluation of Stimuli
10.4.7 Comparing Subjective Attribute Ratings with Objective Signal Features
10.4.8 Conclusion
10.5 Comparative Recording with Several 3D Mic-Arrays at Abbey Road Studios
10.5.1 Microphone Setup
10.5.2 The Recording Process
10.5.3 Binaural Processing in Reaper
10.5.4 Summary and Informal Evaluation
10.6 ‘3D-MARCo’—3D Microphone Array Recording Comparison (Lee and Johnson)
10.7 Informal 3D Microphone Array Comparison (Gericke and Mielke)
10.8 3D Audio Spaced Mic Array Versus Near-Coincident Versus Coincident Array Comparison (Kamekawa and Marui)
10.9 Attempt at a Qualitative Ranking of 3D-Audio Microphone Arrays, Conclusion and Outlook
10.9.1 Qualitative Ranking
10.9.2 Some Thoughts on Localization and Diffuse Sound
10.9.3 Combined Microphone Systems
10.9.4 Relative Volume Levels for Height and Bottom Layers
10.9.5 Introducing an Artificial Head as ‘Human Reference’
10.9.6 BQIrep—Binaural Quality Index of Reproduced Music
10.9.7 FCC (Frequency-Dependent Cross-Correlation) and FIACC (Frequency Dependent Inter Aural Cross-Correlation Coefficient) in 3D Audio Recordings
10.9.8 Conclusion and Outlook
References
Index