This text highlights the importance of human factors in speech technologies and presents and demonstrates the use of human factors, principles, methods, techniques, and tools in the design of speech-enabled applications. Included is coverage of automatic speech recognition, synthetic speech, and interactive voice response systems. Some chapters are devoted to specific applications of speech technology, and other chapters are either issue-oriented or provide a comprehensive view of human factors knowledge and "lessons learned" in a specific applications area. It places special emphasis on interactive voice response (IVR), devoting seven of its fourteen chapters to both speech-enabled and "traditional" touch-tone-based IVR applications. Other chapters emphasize speech recognition application development, natural language processing, synthetic speech, and the use of speech technology in assistive devices for people with disabilities to further the goal of universal access to information technology for all.