Interactions of speaking condition and auditory feedback on vowel production in postlingually deaf adults with cochlear implants

Abstract

This study investigates the effects of speaking condition and auditory feedback on vowel production by postlingually deafened adults. Thirteen cochlear implant users produced repetitions of nine American English vowels prior to implantation, and at one month and one year after implantation. There were three speaking conditions ͑clear, normal, and fast͒, and two feedback conditions after implantation ͑implant processor turned on and off͒. Ten normal-hearing controls were also recorded once. Vowel contrasts in the formant space ͑expressed in mels͒ were larger in the clear than in the fast condition, both for controls and for implant users at all three time samples. Implant users also produced differences in duration between clear and fast conditions that were in the range of those obtained from the controls. In agreement with prior work, the implant users had contrast values lower than did the controls. The implant users' contrasts were larger with hearing on than off and improved from one month to one year postimplant. Because the controls and implant users responded similarly to a change in speaking condition, it is inferred that auditory feedback, although demonstrably important for maintaining normative values of vowel contrasts, is not needed to maintain the distinctiveness of those contrasts in different speaking conditions.

Production and perception of French vowels by congenitally blind adults and sighted adults

“…Interestingly, the opposite pattern was observed, suggesting that the effects of absence of visual feedback on vowel contrasts may be larger than the effects of auditory acuity. ͓Of course, additional unrelated factors, such as differences in language acquisition and socialization, educational environment, etc., may also play a role ͑e.g., Andersen et al, 1993͒.͔ This result is somewhat similar to that reported by Perkell and colleagues ͑Perkell et al, 2004;Ménard et al, 2007͒ on postlingually deaf speakers of American English with cochlear implants. Although several differences exist between the two sets of studies, in the Perkell group's studies, absence of auditory feedback yielded reduced contrast distances between categories in acoustic space, as revealed by reduced AVS values.…”

“…Those parameters have already been used in studies of speech produced by cochlear implant users as measures of produced contrasts ͑Lane et al, Ménard et al, 2007͒. In such studies, for a given vowel contrast, it is assumed that greater contrast distance between vowels reflects greater control and precision in the ability to produce this vowel contrast.…”

“…Following Lane et al ͑2001͒ andMénard et al ͑2007͒, among others, measures of contrast distances between vowel categories were computed. Those parameters have already been used in studies of speech produced by cochlear implant users as measures of produced contrasts ͑Lane et al, Ménard et al, 2007͒.…”

Acoustic and articulatory analysis of French vowels produced by congenitally blind adults and sighted adults

“…The back (rounded) and front rounded vowel categories were significantly larger for blind than for sighted participants, whereas no difference was found for front unrounded vowels. According to Lane et al (2001), Lane et al (2005), andM enard et al (2007), within-category vowel dispersion reflects the precision with which a specific goal is reached. For cochlear implant users, this measure was affected by the experience with the device: the longer the exposure to auditory feedback, the more reduced the within-category vowel dispersion.…”

“…Measures of contrast distances were obtained by computing the Euclidean distances between specific vowel pairs. This measure had previously been used in speech production studies of cochlear implant users (Lane et al, 2001;M enard et al, 2007). Vowels were grouped according to each of the following three phonological dimensions (see Table II): rounding only, place of articulation only, and combination of rounding and place of articulation.…”