Spasmodic Dysphonia (SD) is a voice disorder that causes involuntary spasms or contractions of the vocal cords, interrupting speech and affecting the quality of a person’s voice.

The voice may sound broken, strained, or breathy depending on the type of SD. The two most common types of SD are the adductor type (ADSD), where the vocal cords close together too tightly during certain sounds, and the abductor type (ABSD), where the vocal cords spasm open during certain sounds. Although it can start at any time during life, SD seems to begin more often in middle-age. The disorder affects women more often than men. Onset is usually gradual with no obvious cause.