Improvement in speech-reading ability by auditory training: Evidence from gender differences in normally hearing, deaf and cochlear implanted subjects.
Résumé
Several neuropsychological and neuroimaging studies on gender differences in speech processing lead to the suggestion that women use the neural network of predictive and integrative analysis of speech to a larger extent than men. During speech-reading there is indeed a lack of reliable clues for word recognition which should emphasize predictive and integrative strategies of the brain. Our study aimed to explore gender differences in deaf and cochlear implanted (CI) patients at different levels during speech-reading, for words or phonemes, that we consider, correspond to increased involvement of predictive and integrative analysis. We collected speech-reading scores in a control group of normally hearing subjects (n=42) and in a group of deaf patients - who are good speech-readers - tested before, early after and late after cochlear implantation (n=97). Patient groups were almost equally distributed between follow-up and new patients. In normally hearing controls, women speech-read words better than men. This difference was also observed in all patients but not in experienced cochlear implant users. We did not observe a gender difference during speech-reading of isolated phonemes neither for controls nor for patients. We conclude that the better speech-reading ability of women for words but not for phonemes is in line with their greater use of predictive and integrative strategies for speech processing. Furthermore, we observed a progressive cross-modal compensation in male CI users after cochlear implantation which suggests a synergetic perceptual facilitation involving the visual and the recovering auditory modalities. This could lead to an improved performance in both auditory and visual modalities, the latter being constantly recruited to complement the crude information provided by the implant. Altogether, our data provide insights into cross-modal compensation in the adult brain following sensory privation.