Ever wondered why Robert Kennedy Jr.'s voice sounds unusual? He was diagnosed with a neurological disorder that impacts vocal cords. What to know.

Robert F. Kennedy Jr. started developing symptoms of the condition in 1996. Spasmodic dysphonia is a neurological condition that causes certain muscles in the “voice box,” or larynx, to spasm, often making the voice sound raspy, strained or breathy.

Kennedy's condition is called spasmodic dysphonia, which is a neurologic disorder that can affect the voice and speech by causing the muscles that generate a person’s voice to go into periods of spasm, according to Penn Medicine. It is a lifelong condition, but can be improved with treatment in some cases, according to Penn Medicine.

Robert F. Kennedy Jr. has a disorder called spasmodic dysphonia that makes it sound like his voice is shaking. He has said the neurological disease began to affect him when he was 42. “I have a tremble in my

RFK Jr.'s raspy voice is due to spasmodic dysphonia. The neurological disorder produces muscle spasms in the voice box.

Spasmodic dysphonia (SD), sometimes referred to as laryngeal dystonia, is a rare neurological condition impacting the voice and speech that impacts approximately 50,000 people in North America. For people with SD, muscles spasms in the larynx (also known as the voice box) cause the voice to sound tight, strangled or strained.

Spasmodic dysphonia is a rare neurological disorder that causes involuntary spasms in the vocal cords, making speech strained, breathy, or hoarse.

Spasmodic dysphonia is a rare neurological disorder that causes a strained voice. RFK Jr. says he has had the disorder for decades and treats it with Botox injections, a common treatment.