Bill Hudenko, assistant professor of psychology, and colleagues Wendy Stone and Jo-Anne Bachorowski from Vanderbilt University published an article, titled "Laughter Differs in Children with Autism: An Acoustic Analysis of Laughs Produced by Children with and without the Disorder," in the Journal of Autism and Developmental Disorders.
Article Abstract (Springlink.com)
For their study, the researchers recorded laughter during a series of playful interactions with an examiner. The results showed that children with autism exhibited only one type of laughter, compared to two types of laughter for non-autistic children.
Samples of Laugh Sounds ("Laugh Acoustics of Autism")
There was no difference between the groups on other acoustic measure of laugh duration, frequency, or number of laughs per bout.
Based on their results, Hudenko and his colleagues hypothesize that children with autism may be expressing laughter primarily in response to positive internal states, rather than using laughter to negotiate social interactions.
https://www.ithaca.edu/intercom/article.php/20090626101749125