Faculty Bibliography

OBJECTIVE:To examine changes over time in consonant feature production by children with profound hearing impairments who used either the Nucleus multichannel cochlear implant or the multichannel vibrotactile aid, Tactaid 7. DESIGN/METHODS:Imitative consonant productions of children with prelingual deafness were elicited and transcribed at two intervals: 1) before receiving their respective devices (predevice interval), and 2) after an average of 1.5 yr of device use (postdevice interval). The consonant productions were analyzed in terms of the percentage of consonant features (manner, place, and voicing) produced by the child that matched the features of the examiner's target. The percentage of features produced correctly was then averaged across repetitions, vowel environments, and participants within each group. RESULTS:At the predevice interval, the cochlear implant and Tactaid 7 participants demonstrated similar imitative consonant production abilities. After an average of 1.5 yr of device use, the cochlear implant participants demonstrated significantly greater gains than did the Tactaid 7 participants for the features of voicing and place of articulation. Although the cochlear implant participants showed a trend towards better production of the consonant manner features, this difference failed to reach significance. CONCLUSIONS:The current results suggest that the use of a multichannel sensory aid yields improvements in consonant feature production. Furthermore, use of a cochlear implant appears to promote the production of consonant voicing and place features to a greater degree than does the use of a multichannel tactile aid.

The objective of this study was to determine whether insertion length and number of active channels remained the same after reimplantation of a cochlear implant. A retrospective case review of 170 consecutively implanted multichannedl cochlear implants was conducted. Seventeen of these devices had to be replaced. Data were analyzed for the Nucleus cochlear implant users who were reimplanted in the same ear. For most subjects, insertion length and number of channels remained unchanged, but a few subjects experienced substantial decreases. When the whole group was considered, a small but statistically significant drop was noted for both parameters. In conclusion, although reimplantation is technically possible, the first procedure provides the optimal surgical environment

English-language skills were evaluated in two groups of profoundly hearing-impaired children with the Reynell Developmental Language Scales, Revised. The first group consisted of 89 deaf children who had not received cochlear implants. The second group consisted of 23 children wearing Nucleus multichannel cochlear implants. The subjects without implants provided cross-sectional language data used to estimate the amount of language gains expected on the basis of maturation. The Reynell data from the group without implants were subjected to a regression by age. On the basis of this analysis, deaf children were predicted to make half or less of the language gains of their peers with normal hearing. Predicted language scores were then generated for the subjects with implants by using the children's preimplant Reynell Developmental Language Scale scores. The predicted scores were then compared with actual scores achieved by the subjects with implants 6 and 12 months after implantation. Twelve months after implantation, the subjects demonstrated gains in receptive and expressive language skills that exceeded by 7 months the predictions made on the basis of maturation alone. Moreover, the average language-development rate of the subjects with implants in the first year of device use was equivalent to that of children with normal hearing. These effects were observed for children with implants using both the oral and total-communication methods

The goals of this study were to characterize tongue surface displacement during production of bilabial stops and to refine current estimates of vocal-tract wall impedance using direct measurements of displacement in the vocal tract during closure. In addition, evidence was obtained to test the competing claims of passive and active enlargement of the vocal tract during voicing. Tongue displacement was measured and tongue compliance was estimated in four subjects during production of /aba/ and /apa/. All subjects showed more tongue displacement during /aba/ than during /apa/, even though peak intraoral pressure is lower for /aba/. In consequence, compliance estimates were much higher for /aba/, ranging from 5.1 to 8.5 x 10(-5) cm3/dyn. Compliance values for /apa/ ranged from 0.8 to 2.3 x 10(-5) cm3/dyn for the tongue body, and 0.52 x 10(-5) for the single tongue tip point that was measured. From combined analyses of tongue displacement and intraoral pressure waveforms for one subject, it was concluded that smaller tongue displacements for /p/ than for /b/ may be due to active stiffening of the tongue during /p/, or to intentional relaxation of tongue muscles during /b/ (in conjunction with active tongue displacement during /b/)

The purpose of this longitudinal study is to document improvements in speech intelligibility in children who have received multichannel cochlear implants, to compare their performance to that of a matched group of children with different levels of hearing loss who use conventional hearing aids. Speech intelligibility was measured by panels of listeners who analyzed recorded speech samples preimplant and at 6-month intervals following implantation. The results of this study demonstrate that prelingually deafened children with the Nucleus multichannel cochlear implant achieved significant improvements in speech intelligibility. By the 4.5- to 7.5-year intervals, the speech intelligibility exceeded 40%. $$:

Sound-pressure level (SPL) and fundamental frequency (F0) contours were obtained from four postlingually deafened adults who received cochlear implants and from a subject with Neurofibromatosis-2 (NF2) who had her hearing severely reduced following surgery to remove an auditory-nerve tumor and to implant an auditory brainstem implant. SPL and F0 contours for each phrase in passages read before and after changes in hearing were averaged over repeated readings and then normalized with respect to the highest SPL or F0 value in the contour. The regularity of each average contour was measured by calculating differences between successive syllable means and averaging the absolute values of these differences. With auditory feedback made available, the cochlear implant user with the least contour variation preimplant showed no change but all of the remaining speakers produced less variable F0 contours and three also produced less variable SPL contours. In complementary fashion, when the NF2 speaker had her auditory feedback severely reduced, she produced more variable F0 and SPL contours. The results are interpreted as supporting a dual-process theory of the role of auditory feedback in speech production, according to which one role of self-hearing is to monitor transmission conditions, leading the speaker to make changes in speech postures aimed at maintaining intelligibility

Expressive language skills were assessed in two groups of prelingually-deafened children using the Reynell Developmental Language Scales (RDLS). Results from a group of 89 unimplanted subjects provided cross-sectional data which suggested that profoundly deaf children without implants, on average, could only be expected to make 5 months of expressive language growth in one year. Twenty-three children who received cochlear implants made up the second group of subjects and were administered the RDLS at three intervals: preimplant, 6-, and 12-months postimplant. The scores obtained at the post-implant intervals were then compared to scores that would be predicted on the basis of maturation alone, without the implant (these predictions were formulated based on the data obtained from the unimplanted subjects). At the 12-month postimplant interval, the observed mean language score was significantly higher than the predicted score. Although the mean group data were extremely encouraging, wide inter- subject variability was observed. Although the implant subjects, as a group, were substantially delayed compared with their normal hearing peers, their rate of language growth was found to match that of hearing peers, following implantation. Thus, the gap between chronological age and language age, which normally widens over time in deaf children, remained constant. Preliminary analyses over the first 2.5 years post-implant are consistent with this trend. These results suggest that early implantation (before age 3) might be beneficial to profoundly deaf children because the language delays at the time of implantation would be much smaller