Christine Turgeon

Speech perception relies on auditory and visual cues and there are strong links between speech perception and production. We aimed to evaluate the role of auditory and visual modalities on speech perception and production in adults with impaired hearing or sight versus those with normal hearing and sight. We examined speech perception and production of three isolated vowels (/i/, /y/, /u/), which were selected based on their different auditory and visual perceptual saliencies, in 12 deaf adults who used one or two cochlear implants (CIs), 14 congenitally blind adults, and 16 adults with normal sight and hearing. The results showed that the deaf adults who used a CI had worse vowel identification and discrimination perception and they also produced vowels that were less typical or precise than other participants. They had different tongue positions in speech production, which possibly partly explains the poorer quality of their spoken vowels. Blind individuals had larger lip openings and smaller lip protrusions for the rounded vowel and unrounded vowels, compared to the other participants, but they still produced vowels that were similar to those produced by the adults with normal sight and hearing. In summary, the deaf adults, even though they used CIs, had greater difficulty in producing accurate vowel targets than the blind adults, whereas the blind adults were still able to produce accurate vowel targets, even though they used different articulatory strategies.

According to Perkell’s view [J. Perkell, J. Neurol. 25, 382–407], phonemic goals correspond to multidimensional spaces in the auditory and somatosensory dimensions. The relationships between sensory goals and motor actions in speech are acquired during infancy through feedback-based control mechanisms. Although there have been numerous studies of speech development, little is known about the specific roles of auditory and somatosensory feedback. This paper reviews a few studies of how pre-school-aged children rely on sensory feedback to reach phonemic targets. The studies looked at children with normal-hearing and deaf children with cochlear implants.Vowels and consonants were recorded in various prosodic contexts (neutral and under contrastive emphasis) and perturbation conditions (with or without artificial perturbations of the articulators). Acoustic, articulatory, and perceptual analyses were conducted to assess the degree to which children reached the targets. The data showed that although children’s productions were more variable than adults, children generally adapted their articulatory gestures to produce the appropriate sensory speech goals. The effects of perceptual acuity and phonological knowledge in speech development are discussed.

Studies have reported strong links between speech production and perception. We aimed to evaluate the role of long- and short-term auditory feedback alteration on speech production. Eleven adults with normal hearing (controls) and 17 cochlear implant (CI) users (7 pre-lingually deaf and 10 post-lingually deaf adults) were recruited. Short-term auditory feedback deprivation was induced by turning off the CI or by providing masking noise. Acoustic and articulatory measures were obtained during the production of /u/, with and without a tube inserted between the lips (perturbation), and with and without auditory feedback. F1 values were significantly different between the implant OFF and ON conditions for the pre-lingually deaf participants. In the absence of auditory feedback, the pre-lingually deaf participants moved the tongue more forward. Thus, a lack of normal auditory experience of speech may affect the internal representation of a vowel.