Brigitte Charlier

The rhyming skills of deaf children educated with phonetically augmented speechreading

Two experiments investigated whether profoundly deaf childrens rhyming ability was determined by the linguistic input that they were exposed to in their early childhood. Children educated with Cued Speech (CS) were compared to other deaf children, educated orally or with sign language. In CS, speechreading is combined with manual cues that disambiguate it. The central hypothesis is that CS allows deaf children to develop accurate phonological representations, which, in turn, assist in the emergence of accurate rhyming abilities. Experiment 1 showed that the deaf children educated early with CS performed better at rhyme judgement than did other deaf children. The performance of early CS-users was not influenced by word spelling. Experiment 2 confirmed this result in a rhyme generation task. Taken together, results support the hypothesis that rhyming ability depends on early exposure to a linguistic input specifying all phonological contrasts, independently of the modality (visual or auditory) in which this input is perceived.

Early experience of Cued Speech enhances speechreading performance in deaf.

It is known that deaf individuals usually outperform normal hearing subjects in speechreading; however, the underlying reasons remain unclear. In the present study, speechreading performance was assessed in normal hearing participants (NH), deaf participants who had been exposed to the Cued Speech (CS) system early and intensively, and deaf participants exposed to oral language without Cued Speech (NCS). Results show a gradation in performance with highest performance in CS, then in NCS, and finally NH participants. Moreover, error analysis suggests that speechreading processing is more accurate in the CS group than in the other groups. Given that early and intensive CS has been shown to promote development of accurate phonological processing, we propose that the higher speechreading results in Cued Speech users are linked to a better capacity in phonological decoding of visual articulators.

The neural basis of speech perception through lipreading and manual cues: Evidence from deaf native users of cued speech

We present here the first neuroimaging data for perception of Cued Speech (CS) by deaf adults who are native users of CS. CS is a visual mode of communicating a spoken language through a set of manual cues which accompany lipreading and disambiguate it. With CS, sublexical units of the oral language are conveyed clearly and completely through the visual modality without requiring hearing. The comparison of neural processing of CS in deaf individuals with processing of audiovisual (AV) speech in normally hearing individuals represents a unique opportunity to explore the similarities and differences in neural processing of an oral language delivered in a visuo-manual vs. an AV modality. The study included deaf adult participants who were early CS users and native hearing users of French who process speech audiovisually. Words were presented in an event-related fMRI design. Three conditions were presented to each group of participants. The deaf participants saw CS words (manual + lipread), words presented as manual cues alone, and words presented to be lipread without manual cues. The hearing group saw AV spoken words, audio-alone and lipread-alone. Three findings are highlighted. First, the middle and superior temporal gyrus (excluding Heschl’s gyrus) and left inferior frontal gyrus pars triangularis constituted a common, amodal neural basis for AV and CS perception. Second, integration was inferred in posterior parts of superior temporal sulcus for audio and lipread information in AV speech, but in the occipito-temporal junction, including MT/V5, for the manual cues and lipreading in CS. Third, the perception of manual cues showed a much greater overlap with the regions activated by CS (manual + lipreading) than lipreading alone did. This supports the notion that manual cues play a larger role than lipreading for CS processing. The present study contributes to a better understanding of the role of manual cues as support of visual speech perception in the framework of the multimodal nature of human communication.