I have no idea what an "autistic voice" is but: 5.2 "Hearing and Speech Impairment. An applicant for an FAA certificate issued per part 61, 63, 65, or 107 who cannot hear or speak due to a medical deficiency may be eligible for an FAA certificate with specific operational limitations"
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_60-28B.pdf
However, a diagnosis of autism is going to be a HUGE issue for the FAA. They are paranoid about any kind of mental / cognitive issues - expect expensive testing / documentation at an absolute minimum. And don't be surprised at a denial.
Formal FAA guidelines do not exist
for autism spectrum disorders. Its broad
spectrum of severity and character sug-
gests that each case must be considered
individually. Decisions are based on
review by FA A consultants, psychiatric
and psychological evaluation, and other
tests as needed.
"considered individually" is the FAA dog whistle for "sucks to be you".
One would want to consult with an expert AME such as Dr. Bruce Chien before proceeding with any sort of medical certification (Do not sign up for an FAA medical or fill out the online form. Not no way, not no how.). Or, consider gliders or a light sport certificate.