Acoustic and Perceptual Measurement of Expressive Prosody in High-Functioning Autism: Increased Pitch Range and What it Means to Listeners

Are there consistent markers of atypical prosody in speakers with high functioning autism (HFA) compared to typically-developing
speakers? We examined: (1) acoustic measurements of pitch range, mean pitch and speech rate in conversation, (2) perceptual
ratings of conversation for these features and overall prosody, and (3) acoustic measurements of speech from a structured
task. Increased pitch range was found in speakers with HFA during both conversation and structured communication. In global
ratings listeners rated speakers with HFA as having atypical prosody. Although the HFA group demonstrated increased acoustic
pitch range, listeners did not rate speakers with HFA as having increased pitch variation. We suggest that the quality of
pitch variation used by speakers with HFA was non-conventional and thus not registered as such by listeners.