This study investigated perceptual and acoustical differences in prosody between the speech of young children with autism spectrum disorders (ASD) and typically developing (TD) controls. Seven individuals with a severe ASD diagnosis with ages ranging from 38 to 93 months of age and seven TD controls matched on language-age equivalency with ages ranging from 20 to 30 months of age participated in the study. Spontaneous speech samples were extracted from video recordings of parent-child interactions in which no therapy was provided. In one study, acoustic analyses were conducted to measure speech rate, articulation rate, and aspects of global fundamental frequency (F0). The results of this study revealed a significant difference in mean, maximum, and minimum F0 for the ASD group compared to the TD control group. Moreover, in a second study 18 undergraduate students from the College of Communication Arts and Sciences at Michigan State University blind to the diagnosis of speakers gave perceptual ratings for the 14 ASD and TD speakers on intelligibility, estimated age, pitch, speech rate, degree of animation, and certainty of diagnosis. The results of the study revealed no significant differences in any measure except for estimated age. Taken together, the studies suggest that there are few prosodic differences that distinguish young ASD and TD children matched on expressive language skill, so that prosody may not be a suitable early diagnostic marker of ASD.
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