This volume is one in a series of monographs being issued under the general title of "Disorders of Human Communication". Each monograph deals in detail with a particular aspect of vocal communication and its disorders, and is written by internationally distinguished experts. Therefore, the series will provide an authoritative source of up-to-date scientific and clinical informa­ tion relating to the whole field of normal and abnormal speech communication, and as such will succeed the earlier monumental work "Handbuch der Stimm­ und Sprachheilkunde" by R. Luchsinger and G. E. Arnold (last issued in 1970). This series will prove invaluable for clinicians, teachers and research workers in phoniatrics and logopaedics, phonetics and linguistics, speech pathology, otolaryngology, neurology and neurosurgery, psychology and psychiatry, paediatrics and audiology. Several of the monographs will also be useful to voice and singing teachers, and to their pupils. G. E. Arnold, Jackson, Miss. F. Wincke1, Berlin B. D. Wyke, London Since it was their chatter which prompted the question. this book is dedicated to Sarah and VickY; to Peter who provided some of the answers; to Dorothy in gratitude; and to Him who in the beginning was the Word. Preface These pages are the long-delayed product of questions prompted by the sponta­ neous chatter of my two daughters when they were little. It was only possible to begin to explore these unformed thoughts through the repeated kindness of medi­ cal friends who allowed me to record their new-born children.