 People with adductor or abductor spasmodic dysphonia and healthy volunteers may be eligible for this study. Candidates are screened with a medical history, physical examination, and a test called nasolaryngoscopy. For this test, the inside of the subjects nose is sprayed with a decongestant, and a small, flexible tube called a nasolaryngoscope is passed through the nose to the back of the throat to allow examination of the larynx voice box. During this procedure, the subject is asked to perform tasks such as talking, singing, whistling, and saying prolonged vowels. The nasolaryngoscope is connected to a camera to record the movements of the vocal folds during these tasks. 