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.