We are investigating acoustic and physiologic factors in spastic dysphonia - a voice disorder - in order to provide information about its etiology, typology, and possibly to improve the current diagnostic and treatment methodology. Work completed thus far suggests that: 1) based on acoustic-perceptual and temporal measures of voice and speech, the currently used diagnostic procedure comprising temporary unilateral chemical paralysis of a recurrent laryngeal nerve (RLN) is a good predictor of the changes in phonation occurring immediately postsurgically; 2) perceptual differences pertaining to the injection side (left vs. right) are not significant; 3) RLN section remains the preferred surgical technique; 4) spasticity may recur when the motion of the vocal fold returns; 5) histopathologic findings appear controversial but are under investigation; 6) neurologic data, although not directly pointing to causality of spastic dysphonia, supports regarding the disorder as organic; 7) surgery of the RLN provides patients with immediate relief of symptoms, and appears to create long-lasting improvement in the majority of those treated by this method; and 8) more normal voice initiation and termination is achieved by a paralyzed larynx than by a "spastic" larynx.