Perception and production of the voiced/voiceless stops and oral/nasal vowels in cochlear implanted children.

The contribution of the cochlear implant to language development is undeniable: implanted deaf children are able to acquire high linguistic skills and intelligible speech over a period of time quite similar to that of normal-hearing children. However, in comparison with normal-hearing children, deaf children with CI still exhibit some persistent language difficulties. It is sensible to assume that the persistence of atypicalities is due to the fact that children with CI develop their speech and language production and perception skills under limited sensory capabilities, the input acoustic bandwidth being reduced and exploited through a small number of transmission channels. The studies presented have investigated phonetic and phonological skills of the cochlear implanted children, compared to normal-hearing children. A first study have focused on the voiced and voiceless stops. We analyzed both perception and production - with acoustic measures (VOT values). A second study have focused on oral and nasal vowels, also with perception and production tasks - with acoustic measures allowing to characterize the oral/nasal distinction of the productions. In perception, CI children seem to have a less categorical effect for the voicing contrast for stops, maybe caused by imprecise phonological categories. For vowels, we have seen fewer skills of identification and discrimination of oral and nasal vowels, suggesting an imprecise processing of the spectral information. In production, despite similar performances in the production tasks, we see different phonetic realizations for occlusive consonants: CI children showing shorter VOT values, and also for vowels, saw in the two first formants values, euclidean distances and bandwidth of first formant. The investigation of language components skills in CI and NH children can provide clinical benefits by improving diagnosis, theoretical basis of remediation and associated tools; but also for providing a better comprehension of the language acquisition mechanisms for both NH and CI children.