I have attempted to prepare this volume in such a way as to provide a source of information on the normal physiology of speech and song as well as on the disorders of those functions. To the extent that I have succeeded it should be of interest to physiologists, physicians, and teachers and students of the VOlce. The book is by no means a text on laryngology, nor is it a treatise on the physiology of breathing mechanics, nor yet is it a manual telling how to teach or learn voice production. If none of these, what is it? It is a discussion of the application of breathing mechanics to phonation of interest to the respir-- atory physiologist, of certain aspects of physiology and medicine of interest to the teacher or student of voice, and of the problems of voice production and its maladies of interest to the laryngologist. I have undergone a number of experiences during the past 50 years which I believe have qualified me to undertake this task with some special hope of success. In my youth I studied voice for twelve years with four outstanding teachers and performed publicly as a lieder singer, in oratorio, chorus, and opera. Later I trained for and entered the medical profession in the specialty of otolaryngology. Later still I engaged in research on the physiology of breath- ing mechanics and phonation, especially singing.