Perceptual and Acoustic Measures of Prosody in Individuals with Autism Spectrum Disorder and First-Degree Relatives
Objectives: To assess perceptual and acoustic measurements of prosody in individuals with ASD and their parents.
Methods: Individuals with ASD (n=26), their parents (n= 43), and respective control groups (n=16 ASD controls; n=30 parent controls) completed the PEPS-C, which was rated by blinded coders. Responses to the expressive subtests of the PEPS-C from a subset of participants (ASD n=5; proband controls n=6; ASD parents n=14; parent controls n=10) were further characterized with acoustic analysis using Praat (Boersma, 2001) to obtain measures of mean fundamental frequency (f0), standard deviation (SD) of f0 and f0 range, both measures of f0 variability (acoustic analysis of data from the full sample is ongoing). Additionally, correlational analyses were conducted to examine relationships between these measures.
Results: Individuals with ASD and their parents exhibited poorer prosodic imitation, lexical stress expression, and contrastive stress expression (ps<.05). Individuals with ASD also demonstrated significantly greater atypicalities in phrase stress expression (e.g., “I saw a blue bird” vs. “I saw a bluebird”) compared to controls, and this difference was marginal between the parent groups, with the ASD parent group demonstrating greater atypicalities (p=.05). Of the seven receptive subtests, individuals with ASD performed more poorly than controls only in their understanding of contrastive stress (p<.01). Acoustic analyses did not reveal significant differences in the ASD (ps>.67) or parent groups (ps>.61). Decreased f0 range was associated with ratings of poorer contrastive stress ability in ASD parents (r= .60, p=.04).
Conclusions: Individuals with ASD and their parents demonstrated greater prosodic atypicalities across several domains of the PEPS-C based on perceptual ratings. However, consistent with prior work, these differences were not readily apparent based on acoustic measures of prosody (Diehl et al., 2013), although associations in the ASD parent group suggest that perceptual differences may be related to decreased f0 variability. The large overlap between subtests in which individuals with ASD and their parents differed from their respective control groups highlights the domains of imitation, lexical stress, and contrastive stress as potentially key areas contributing to overall perception of prosodic atypicalities during conversational interactions. Ongoing analyses including a larger sample size will further investigate acoustic differences and relationships with perceptual ratings of prosody in all groups.