Thesis defence : Laura MACHART

Thesis defence

On 12 October 2022

Speech production in deaf children : benefits of exposure to French Cued Speech in combination with cochlear implantation

Although cochlear implant (CI) improves speech perception in children with hearing impairment, the perception of some acoustic features may be impaired and oral language development impacted, with limited phonological skills. In order to supplement missing phonological information, the manual gestures of French Cued Speech or Langue française Parlée Complétée (LfPC) can be used simultaneously with speech. Several studies have shown the benefits of exposure to cued speech on speech perception and phonological development of the child with hearing impairment. However, few studies have examined the link between cochlear implantation and cued speech. This thesis proposes to investigate the long-term benefits of exposure to Cued French (CF) for the phonological development of children with cochlear implants. Our general hypothesis is that exposure to CF improves speech perception, which promotes the development of phonological representations in children with CI. We hypothesize that the phonological skills developed in perception, through exposure to CF, transfer to speech production, which would improve phoneme production. This improvement was demonstrated using acoustic data (picture naming task) and then characterized using articulatory data.First, the speech production of fourteen children with cochlear implants and 71 children with normal hearing, aged 60-140 months, was analyzed using the EULALIES picture naming task, which is designed to test the accuracy of spontaneous (non-imitative) phoneme production in an isolated word context. Analysis of these data by expert phoneticians allowed us to show a significant improvement in the speech production abilities of eight children with cochlear implants when they developed a high level of CF reading skills, compared to six children who had little or no CF reading skills. Like many studies, our results indicate that early implantation facilitates the development of phonological skills, but that the production of some phonetic features, such as voicing and nasality contrasts and mode and place of articulation, remain impaired even in children with early implantation. On the other hand, our analyses show that a high level of CF reading skills reduces the number of errors on these phonetic features: our data highlight that adequate exposure to CF seems to improve the production of voicing, nasality contrast and mode and place of articulation.In a second step, the acoustic productions and articulatory gestures, collected by lingual ultrasound, of nine children with cochlear implants exposed to CF and ten children, aged 51-137 months, were studied. The results suggest that exposure to CF enables children with cochlear implants to produce articulatory language gestures in the same way as their normal hearing peers, especially when they have developed high CF reading skills. Our data also demonstrate that a high level of CF reading skills promotes place of articulation distinction in plosives and fricatives in children with CI.As several research teams have argued, exposure to CF is functionally beneficial during communication as it provides visual access to all French phonemes. Furthermore, the results of these two studies highlight its longer-term effects on speech production, probably explained by the fact that better perceptual access provides better phonological representations.This thesis also provides two sets of baseline data on the speech production of typically developing children and children with cochlear implants: a phonetic data set and an acoustic and articulatory data set. These data can inform clinical practice by providing guidance for speech and language therapy interventions to facilitate the care of children with cochlear implants, but also to support daily interactions at home by confirming the crucial role of visual cues for optimal development of speech production and processing.
 
Encadrants :
- Directeur de thèse : Hélène LOEVENBRUCK -  helene.loevenbruckatuniv-grenoble-alpes.fr (helene[dot]loevenbruck[at]univ-grenoble-alpes[dot]fr)
- Co-encadrant : Anne VILAIN -  anne.vilainatgipsa-lab.grenoble-inp.fr (anne[dot]vilain[at]gipsa-lab[dot]grenoble-inp[dot]fr)
 
Keywords of the thesis: cochlear implant, Completed Spoken French Language, speech production in children, phonological representations, acoustic data, articulatory data,
 

Date

On 12 October 2022

Financement

Projet HearCog - ANR-17-CE28-0006

Submitted on 20 November 2023

Updated on 20 November 2023