Robert F. Kennedy Jr. suffers from a condition called spasmodic dysphonia, which is a specific form of an involuntary movement disorder called dystonia that affects only the voice box. This chronic neurological voice disorder and focal laryngeal dystonia results in involuntary spasms of the muscles that open or close the vocal cords, causing the voice to sound strained, hoarse, and sometimes barely audible. There is no cure for the condition, but patients can undergo speech therapy or counseling to manage the symptoms.