Auditory-Visual Perception of VCVs Produced by People with Down Syndrome: Preliminary Results

Down Syndrome (DS) is a genetic disease involving a number of anatomical, physiological and cognitive impairments. More particularly it affects speech production abilities. This results in reduced intelligibility which has however only been evaluated auditorily. Yet, many studies have demonstrated that adding vision to audition helps perception of speech produced by people without impairments especially when it is degraded as is the case in noise. The present study aims at examining whether the visual information improves intelligibility of people with DS. 24 participants without DS were presented with VCV sequences (vowel-consonant-vowel) produced by four adults (2 with DS and 2 without DS). These stimuli were presented in noise in three modalities: auditory, auditory-visual and visual. The results confirm a reduced auditory intelligibility of speakers with DS. They also show that, for the speakers involved in this study, visual intelligibility is equivalent to that of speakers without DS and compensates for the auditory intelligibility loss. An analysis of the perceptual errors shows that most of them involve confusions between consonants. These results put forward the crucial role of multimodality in the improvement of the intelligibility of people with DS.