Audio Bandwidth Extension: Application of Psychoacoustics, Signal Processing and Loudspeaker Design
Bandwidth extension (BWE) refers to various methods that increase either the perceived or real frequency spectrum (bandwidth) of audio signals. Such frequency extension is desirable if at some point the frequency content of the audio signal has been reduced, as can happen for example during recording, transmission or reproduction. This volume, significant in dealing exclusively with BWE, discusses applications to music and speech and places particular emphasis on signal processing techniques.It presents an all-encompassing approach to BWE by covering theory, applications and algorithms. It reviews important concepts in psychoacoustics, signal processing and loudspeaker theory. It develops the theory and implementation of BWE applied to low-frequency sound reproduction, perceptually coded audio, speech and noise abatement. It includes a BWE patent overview. "Audio Bandwidth Extension" pulls together recent developments in to a single volume and presents a coherent framework to the reader. Such an approach will have instant appeal to engineers, specialists, researchers and postgraduate students in the fields of audio, signal processing and speech.
Why Read This Book
You will get a focused, application-driven treatment of audio bandwidth extension (BWE) that ties psychoacoustics to practical signal-processing algorithms and loudspeaker concerns. The book shows how to restore or perceptually extend missing spectral bands in speech and music and how to evaluate those methods perceptually and technically.
Who Will Benefit
Practicing audio and speech engineers, codec developers, and DSP researchers who need techniques for restoring or perceptually enhancing lost frequency content in recorded, transmitted, or reproduced audio.
Level: Intermediate — Prerequisites: Basic DSP (FFT, filtering, spectral analysis), fundamentals of audio/speech processing, and familiarity with perceptual audio concepts (masking, critical bands).
Key Takeaways
- Explain psychoacoustic principles relevant to perceived bandwidth and masking that underpin BWE methods.
- Design and implement common bandwidth-extension strategies (e.g., spectral band replication, harmonic transposition) for speech and music.
- Evaluate bandwidth-extension algorithms using objective measures and subjective listening tests.
- Integrate BWE modules with perceptual audio codecs and real-time playback chains.
- Apply low-frequency extension techniques and loudspeaker considerations to improve reproduced bass for small speaker systems.
- Choose appropriate algorithm/parameter trade-offs for complexity, latency, and perceptual quality in real-world systems.
Topics Covered
- 1. Introduction to Bandwidth Extension: Definitions, Goals, and Use Cases
- 2. Fundamentals of Human Hearing and Psychoacoustics
- 3. Signal Analysis Tools for BWE: Spectral Representations and Perceptual Transforms
- 4. Low-Frequency Extension and Loudspeaker Considerations
- 5. High-Frequency Extension Techniques: Harmonic Generation and Transposition
- 6. Spectral Band Replication (SBR) and Related Techniques
- 7. BWE for Speech: Models, Implementation, and Examples
- 8. BWE for Music: Challenges and Approaches
- 9. Integration with Perceptual Coding and Codec-Compatible Methods
- 10. Objective and Subjective Evaluation Methodologies
- 11. Real-Time Implementation Issues and Complexity Reduction
- 12. Case Studies and Practical Examples
- 13. Conclusions and Future Directions
Languages, Platforms & Tools
How It Compares
More narrowly focused on BWE and psychoacoustics than broad DSP texts like Udo Zölzer's 'Digital Audio Signal Processing', and complements codec/SBR literature (e.g., MPEG SBR papers) by tying algorithmic detail to loudspeaker and perceptual evaluation.
