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...