Stemming from the great volume of research done in this field at the Bell telephone laboratories, this book is the developed logically from a single general problem. If a talker (T) of described characteristics speaks into a transmission system S of described characteristics, how well will a listener recognize the sounds spoken at T? To provide the great range of information needed to enable the reader to deal properly with this problem, this book deals with three issues: 1. A fundamental description of the speaking process and the speech waves created by talking as well as the methods of describing the Talker (T). 2. The hearing process in the methods of describing the listener. 3. The interaction of the Talker (T) and the system (S) and the Listener. Thoroughly revised and substantially rewritten, this new second edition brings every phase of the subject up-to-date. For example, Chapter 14, the space-time pattern of hearing is entirely new, and gives a mathematical treatment of the dynamics of the hearing process. The results of this analysis are in the excellent agreement with the epochmaking experimental results of Bekesg, and mark a significant milestone in our understanding of the mechanism of hearing. This book appeals to those interested primarily in speech, such as teachers of speech and phonetic experts, to those interested chiefly in hearing such as otologists, audiologists and workers and hearing clinics, and to those interested in many applications of the subject, such as electrical, communications and radio engineers. Illustrated with charts, diagrams and graphs.