Production and Perception of Affective Prosody by Adults with Autism Spectrum Disorder
Hubbard, Daniel James
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Affective prosody, defined as the use of paralinguistic elements in speech to convey emotion, is important for effective social functioning. While generally a trivial task for typically-developing (TD) adults, individuals with autism spectrum disorder (ASD) present with significant challenges in social communication and interaction, including prosody. Previous research has shown that talkers with ASD produce pragmatic prosody with increased variability in fundamental frequency (f0, which is closely correlated with voice pitch), but it was unclear whether those differences carry over to speaking tasks involving emotion elicitation. A controlled set of expressive speech recordings was obtained from talkers with ASD and controls in five emotion contexts: angry, happy, interested, sad, and neutral. Emotion-specific group differences in f0, intensity, and duration were found in multiple speech types, and the pattern of results was characterized by inconsistent and exaggerated patterns of affective prosody production in talkers with ASD compared to controls. The perceptual relevance of the affective acoustic differences was tested in three listening experiments involving talkers and listeners with ASD and controls. The first two experiments involving TD listeners were designed to examine the perceptual impact of increased f0 variability and intensity found in recordings produced by talkers with ASD. Compared to the intensity manipulation, modifying the f0 contour had a larger impact on emotion recognition accuracy. The third experiment was designed to compare perception of affective prosody in listeners with ASD and controls using unmodified stimuli, and revealed that differences in affective prosody perception were more closely related to talker group production differences than listener group differences. The results are consistent with previous work in face perception showing increased emotion identification rates but lower naturalness ratings when listeners responded to stimuli produced by individuals with ASD. The findings are interpreted within the context of the speech attunement framework, which suggests that individuals with ASD lack the motivation to attune their prosodic speech to sound like TD talkers.