Robert F. Kennedy Jr.'s distinctive raspy and strained voice is caused by a rare neurological condition called spasmodic dysphonia. This disorder leads to involuntary spasms in the muscles that control the vocal cords, causing breaks, a strained or strangled quality, or breathy tones in the voice depending on the type of spasmodic dysphonia he has

. Spasmodic dysphonia is a chronic neurological voice disorder classified as a focal laryngeal dystonia. It affects about 1 in 50,000 to 100,000 people worldwide, with a higher prevalence in women. The exact cause is unknown but is believed to involve abnormalities in brain regions that regulate movement, such as the basal ganglia and cerebellum

. Kennedy has spoken openly about how the condition affects him, expressing frustration with his voice and noting that it worsened gradually over time. He has treated it with Botox injections, which relax the vocal muscles, though he eventually stopped this treatment as it was not a perfect fit for him. Despite the vocal challenges, the condition does not affect other vocal functions like laughing or shouting

. In summary, RFK Jr.'s voice is affected by spasmodic dysphonia, a neurological disorder causing involuntary muscle spasms in the vocal cords, resulting in his characteristic raspy, strained, and sometimes tremulous voice