Leybaert, J. 1 , Berthommier, F. 2 & Huyse, A. 1
1 Université libre de Bruxelles
2 Gipsa-Lab
The study aimed to test whether audio-visual speech integration in cochlear-implanted (CI) children and in normally hearing children exposed to degraded auditory stimuli is impacted by the degradation of the visual speech information. A group of 31 children with CI and a group of 31 normally hearing children (who received spectrally reduced speech), matched for chronological age, performed a syllable identification task where stimuli were presented randomly in auditory only (AO), visual only (VO) and audiovisual (AV) (congruent and incongruent McGurk stimuli). The visual speech cue was normal in half of the experiment, and degraded in the other half. Results show that performances in VO and in congruent AV modalities were decreased in visual reduction, showing that our technique was efficient at degrading lip- reading. Visual reduction also led to a major increase of auditory-based responses to McGurk stimuli in hearing as well as in deaf children, and this increase of auditory responses was larger in children who were proficient in the use of their implant. The increase of the weight of audition, including in cochlear-implanted children whose perception is generally dominated by vision, suggests that the natural imbalance in favour of vision is not immutable.