Not long ago, I talked to a young man about my love of Abbott and Costello. The young man had never seen an Abbott and Costello film and I offered to loan him a DVD of Hold That Ghost (1941). I must have been persuasive in my praise of the comedy team because my friend didn't wait long after I gave him the film to bring it home and pop it into his DVD player. He flashed me a big grin when I saw him the next day, which let me know that he did enjoy the film. Then, he told me something that caught me by surprise. He revealed to me that he suffered from Tourette syndrome and he said that he was particularly amused by Costello because the comedian expressed a variety of phonic tics that are commonly associated with Tourette syndrome. Most common of the repetitive sounds that Costello uttered in his comic performance were wheezing, whistling and humming. I found it intriguing that the way in which a high-energy comedian used vocal sounds to punctuate a line or express an emotion (usually fear, lust or frustration) could make him relatable to a person who suffer from a neurological disorder. Motor tics, which are also caused by Tourette syndrome, are something that can be seen in the work of many comedians. These tics can include facial grimacing, eye blinking, shoulder shrugging and head jerking. Abnormalities in the nervous system cause exaggerated reactions, which can mirror the exaggerated reactions that we see in comedy performances.
Below is a compilation of Costello's funny vocalizations in Hold That Ghost.
Mel Blanc emphasized Costello's whistling tic when he parodied the comedian for a 1942 Warner Brother's cartoon, A Tale of Two Kitties.
I recommend a new book on Abbott and Costello's Buck Privates (1941), which was written by Abbott and Costello authority Ron Palumbo.