Audiovisual Speech Perception in Autism

Background: There is evidence that during the development of the speech perception, auditory and visual features are necessary to understand a linguistic message. Different speech perception deficits are implicated in children with autism spectrum disorders (ASD). However, we don’t know exactly what are the mechanisms involved in these disorders during the integration of auditory and visual features by ASD children. Previous studies are not clear whether ASD children proceed to lip-reading and integrate speech auditory and visual features, and whether face processing and mirror neurons are implicated.

Objectives:  This study examined the perception profile of the speech sounds in the visual and auditory-visual modalities in ASD children with and without language delay (High-Functioning Autism- HFA)/Asperger syndrome-AS).

Methods: We compared two groups of children diagnosed HFA and AS matched with one group of typically developed children aged between 9-12 years. We used behavioral speech perception tests with natural stimuli (vowels and consonants) in visual modalities (lip-reading) and audiovisual stimuli with the static and dynamic faces, either full face view or partial view (only the mouth).  

Results: The results revealed that ASD children have a deficit in the visual speech modality (lip-reading) but not in the integration of visual with auditory speech features. AS also have more difficulty with complexe stimuli, such as consonants in full face view. HFA children have a categorical precision deficit in the identification of vowels and consonants in visual modalities (lip-reading) independently of the nature of the stimuli (vowels/consonants, static/dynamic faces, full face view/partial view).

Conclusions: These findings suggest, a deficit in the maturation of the cerebral regions implicated in the coupling between auditory and visual speech features in children with autism. These results are discussed in relationship with language and social abilities deficits in autism.

Keywords: lip-reading, audiovisual integration, speech, vowels, consonants, autism.