Receptive and Expressive Prosody of Individuals with Asperger Syndrome

Author: Kate King

King, Kate, 2012 Receptive and Expressive Prosody of Individuals with Asperger Syndrome, Flinders University, School of Medicine

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Effective communication requires understanding of other people’s use of prosody (intonation, stress and rhythm) as well as the ability to produce appropriate prosody. Expressive prosody in autism spectrum disorders (ASD) is often described as unusual and limited research has been conducted. Difficulties with receptive prosody are often assumed, acoustic analysis has rarely been utilized to determine prosodic characteristics and the majority of studies have involved small sample sizes. The cause of the dysprosody is currently thought to result from the social and cognitive impairments associated with ASD. However, impaired motor abilities have also been determined in the speech of individuals with ASD, so could be a concomitant cause of the prosodic disturbance. This study sought evidence of impaired speech production processing in the prosody of participants with Asperger syndrome (ASP), one of the autism spectrum disorders. ASP (n=58) were diagnosed through Autism SA. To gain a broader knowledge of prosody in AS and to facilitate comparisons, understanding and expression of prosodic functions (including grammatical, pragmatic and affective prosody) and of reading tasks requiring application of typical English rhythm were assessed. Spontaneous speech was also examined. Results of perceptual analysis and of acoustic analysis which included intensity (loudness), minimum, maximum and average pitch, pitch range and duration were compared with the results for control participants (CP). CP (n=50) did not have a diagnosis of ASD, language disorder or intellectual disability and were matched by age, gender and educational status to the ASP. With one exception (understanding of pragmatic prosody) ASP understood all domains of prosody as well as CP, however, clear evidence of a consistent deficit in prosodic production was found. ASP produced significantly more errors than their matched CP with pragmatic, affective and grammatical prosodic functions producing statistically significantly differences. The ASP were also less able than the CP to apply typical English rhythm. Acoustic analysis of spontaneous speech samples did not reveal significant differences, but statistically significant results were found in the reading condition, with the ASP using a higher mean minimum pitch and longer durations than the CP. Pitch difficulties and longer durations are indicative of speech motor impairment. Speech production difficulties were also observed in the high incidence of residual articulation substitutions and the increased speech dysfluencies made by the ASP. Overall, the result that receptive prosody was virtually intact while production across both linguistic and non-linguistic domains was significantly poorer for ASP than for CP indicates that speech motor functioning is likely to underpin the prosodic disturbance in Asperger syndrome. This research involves a larger number of subjects than all previous studies internationally and includes receptive and expressive prosody as well as acoustic analysis, therefore adding considerably to the limited information available on prosody in ASD. As motor difficulties have been shown to affect prosody in ASP, intervention should include amelioration of expressive prosody issues and should not concentrate solely on social/emotional factors.

Keywords: Asperger syndrome, prosody, ASD, autism spectrum disorders, Asperger's syndrome, speech disorders, communicative disorders, speech therapy, interpersonal communication, Psycholinguistics, Verbal behavior
Subject: Medicine thesis, Speech Pathology thesis, Audiology thesis

Thesis type: Doctor of Philosophy
Completed: 2012
School: School of Medicine