Customer Reviews

Digital Speech: Coding for Low Bit Rate Communication Systems

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This book has some good background material on speech coding plus some material on new speech processing and coding techniques. In order to lay the foundation of speech coding technology the book reviews sampling, quantizations, and then the basic nature of speech signals and the theory and tools applied in speech coding. The last two chapters of the book consists of some recent research in the areas of voice activity detection and speech enhancement.

This book shows a real disconnect in style between its first nine chapters and the last two. The first nine are very well written and cover all the basics of speech coding. The mathematical aspects of speech coding are clearly laid out and derived, and the book makes liberal use of some very good illustrations that model various parts of speech coders in block diagram form. In order to understand all of this, though, you should already have a good grasp of digital signal processing and probability theory including random processes. Particularly good are the discussions on the short-time Fourier transform of speech and the effects windowing has on it, the long-term prediction of speech, and pitch detection methods. The last two chapters are written like research papers, and are not very clear at all. There is quite a bit of probability theory on display there, and the notation is hard to discern. There are no exercises at all in this book, but each chapter does have a pretty good summary, even the research chapters.

I would say if you want to learn about speech coding this is a good economical way to learn, although I think Speech Coding Algorithms: Foundation and Evolution of Standardized Coders by Chu is probably a better book for beginners. You might want to stop reading after chapter nine of this book unless you are just extremely interested in the research portion.