People with ASD are often reported to speak in a noticeably different way. We have conducted acoustic analyses of speech to understand whether there are common ways speech differs and the details of how it does (e.g., in intonation, volume, speed). We also examine how listeners perceive the speech, which is has an important impact on social interactions.
Contrary to the stereotype of monotone speech, we found that children with ASD displayed more variable rather than flat intonation. We also collected perceptual ratings to see if listeners picked up on these differences. While they rated speakers with ASD as more atypical overall, their ratings of intonation variability were less consistent. It appears that although speakers with autism may use a greater intonation range than their peers, this is not translated as more emotional or dramatic speech to listeners - instead, listeners did not know what to make of it, which indicates to that intonation patterns may be used in unusual ways.
In a second study, we investigated how speakers make something more salient with acoustic cues, e. g. ‘‘Pick up the BIG cup.” We found that speakers with ASD did this very similarly to a typically developing comparison group, marking salience in the expected location. Both groups of speakers employed amplitude and duration to mark the contrastive element, rather than pitch. However, the groups also differed in their relative reliance on amplitude versus duration.