Speech pathology is concerned with deviations in speaking behavior that significantly reduce communication effectiveness. Organic causes of speech disorders include defects of peripheral speech organs, neuromuscular defects, and sensory defects—for example, significant hearing loss. In many cases, there is no apparent organic defect sufficient to explain the speech disorder. An understanding of abnormal speech obviously presupposes knowledge concerning the normal processes of speech and language. Thus, the speech pathologist has a particular interest in research concerning the speech-generating processes and their relationships to the nature of the speech output. Recent work concerning speech articulation and the probable relationships of underlying neural events to the control of articulatory processes is of special significance to speech pathology. Studies directed toward better understanding of the fundamental time segments of the speech stream is of particular interest because of implications concerning the behavioral units with which the speech pathologist must deal. Other research areas of special interest include study of the aerodynamic relationships required for speech generation and further research into the functioning of the larynx as a sound source.