My child has high functioning autism but feels an urge to make weird sounds that he can not stop?

One idea. Asperger's / high function autism can run with Tourette's. I have a physician colleague who has this and is easily managed by a specific medication. Best wishes.
Yes.... That is part of self stimming behavior common in autism spectrum disorder. Have you talked to or seen an autism specialist? Have you trued diet changes? Has he seen a neurologist (?Tic issue). Allergies can sometimes contribute.
Possibilities are. Compulsion, vocal tic or stereotypy, that probably increases when he's anxious. Usually it can be treated with Clonidine or long-acting guanfacine, but it sometimes requires neuroleptics. If his cognitive ability is in the "average" range or above & his receptive & expressive language abilities are adequate, cognitive-behavioral therapy or specific habit-reversal therapy may help.