This introduction to speech interfaces is intended for readers familiar with graphical user interfaces but new to speech interfaces. It consists of four parts, which cover concepts, technology, guidelines, and processes.

Part 1 briefly explains the relevant fundamental concepts, ranging over the physics of sound, the physiology of speech, a variety of concepts related to natural languages and speech, and human factors related to speech technology. Unfortunately, this part suffers from careless writing: “sound wave” is not synonymous with “sine wave,” nor is a wavelength the distance between a peak and a trough (both on page 47); also, the loudness of a sound is not “determined by the size of its wavelength” (p. 49).

Part 2 describes basic technologies--software, hardware, recognition and synthesis, and the use of natural languages in computer applications. Of particular interest are the descriptions of current commercial products, which will be useful to anyone who needs to follow up on applications, even though they will undoubtedly be outdated soon.

Parts 3 and 4 address design issues. Part 3 contains “laws” and guidelines for designing speech interfaces. The “laws” are actually principles of speech interface design, distilled from widely accepted principles of design applicable to all kinds of user interfaces and adapted for the design of speech interfaces. Twenty principles are given, which may be too many--some could profitably be combined to shorten the list. The bulk of chapter 9 explains and justifies each principle, with reference to constraints imposed by human factors and technological considerations. Unfortunately, the chapter begins with a list of the laws, with no explanation: one must read the discussion of each law later in the same chapter. Chapter 10 consists of guidelines for design--specific rules for operational implementations of the principles of chapter 9 in real interfaces.

Part 4 deals with interface design and usability engineering. Chapter 10 is a well-organized description of the authors’ method for designing speech interfaces. Tools and techniques for the design method are described in this chapter, which is liberally endowed with aids to comprehension, such as tables of process steps. Detail is sometimes lacking, though, and readers might benefit from more links between mentions of specific tools and techniques and pointers to more information about them. A short chapter on universal design, that is, designing interfaces that can also be used by people with disabilities, completes Part 4.

A timeline for speech technology, a glossary, and a compilation of resources (Web sites, books, and papers) are included as appendices to round out the book. The bibliography’s coverage is fairly wide, though not comprehensive. Combining the bibliography with the list of resources in Appendix C would be a good idea for a second edition (perhaps as an annotated bibliography organized by chapter), because it is a little confusing to have to look for sources of more information in two different places.

Interviews with practitioners and researchers are appended to some chapters, and contribute to the book by advancing the reader’s knowledge as well as providing a perspective from the field. The content is substantial and useful; the organization of information is competent; the presentation, typography, and illustrations are generally good; and the expression is clear. In short, this book is informative and educational.