Emergence of a vowel system in a young cochlear implant recipient.

This report chronicles changes in vowel production by a congenitally deaf child who received a multichannel cochlear implant at 19 months. The emergence of Hannah's vowel system was monitored by transcribing vocalic segments from spontaneous utterances produced during two 30-minute recording sessions before implant surgery and 12 monthly recording sessions after her implant was activated. Vowel types were included in her inventory whenever transcribers independently agreed that a vocalization contained an allophone of a given vowel type. Hannah exhibited three vowel types before implantation. A total of nine different vowel types were observed during her first year of implant experience, and a full range of place and height categories was represented. Acoustic analyses revealed that Hannah's vowel space was near normal in size and that the formant structures of /i/ and /u/ were distinctive from other point vowels. Formant regions for /ae/ and /a/ showed some overlap. Taken together with a previous report of her vocal development (D. J. Ertmer & J. A. Mellon, 2001), Hannah appears to have made substantial progress in speech development during her first year of implant use.

Beginning to talk at 20 months: early vocal development in a young cochlear implant recipient.

Early vocal development, consonant production, and spoken vocabulary were examined in a deaf toddler whose multichannel cochlear implant was activated at 20 months. Parent-child interactions were recorded before implantation and at monthly intervals during the first year of implant use. The child's utterances were classified according to developmental levels from the Stark Assessment of Early Vocal Development. The emergence of consonant types and consonant features were documented through listener transcription. Parent reports were used to monitor oral vocabulary growth. A large increase in canonical and postcanonical utterances was observed after 5 months of implant use, and these advanced prelinguistic forms were dominant in all subsequent recording sessions. Increases in the diversity of consonant types and features suggested that auditory information was used to increase phonetic diversity. It was reported that the child understood almost 240 words and spoke approximately 90 words after one year of implant experience. The combination of cochlear implantation at a young age, family support, and regular intervention appeared to facilitate efficient early vocal development and gains in spoken vocabulary.

A comparison of speech training methods with deaf adolescents: spectrographic versus noninstrumental instruction.

The effects of speech training with real-time spectrographic displays (SDs) were examined and compared to the effects of noninstrumental (NI) instruction (i.e., training without computerized displays of speech) for deaf adolescents. A single-case modified alternating-treatment experimental design with replication across subjects and speech targets was used to examine within-subject performance in establishing, maintaining, and generalizing target consonants. Comparisons between the two approaches were accomplished by determining how frequently each method resulted in improvement, maintenance of improvement, and generalization to untrained words. Each of the 4 subjects demonstrated improvement under both forms of instruction in a relatively short time. Maintenance of improvement was observed 6 weeks post-treatment for two NI-trained targets and one SD-trained target. Two subjects showed better generalization for their SD-trained target than their NI target. There was little difference in generalization scores for the remaining subjects. All subjects either regained their highest previous levels of acceptability or maintained high-level acceptability following brief, independent practice with SDs 10 weeks after training was discontinued. The expediency of independent practice with SDs was discussed.

Imitative consonant feature production by children with multichannel sensory aids.

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: 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.

A comparison of vowel production by children with multichannel cochlear implants or tactile aids: perceptual evidence.

OBJECTIVE: To examine changes in perceived vowel production accuracy over time in prelingually deafened children who use a multichannel cochlear implant (Nucleus 22 channel) or a multichannel tactile aid (Tactaid 7) and to compare the levels of perceived vowel production accuracy attained by the two device groups. DESIGN: The subjects were participants in longitudinal studies of the effects of sensory aids on the development of perceptual, speech, and language skills. As part of these studies, imitative vowel productions were elicited and transcribed before each child received their sensory aid and at 6 mo intervals thereafter. Data for the current study was obtained from the predevice interval and a later interval (postdevice) that was an average of 1.8 yr after the subjects received their respective devices. The subjects' vowel productions were judged for accuracy in matching an imitative model and for correctness of vowel features (height and place). Within-group analyses were completed to determine if vowel production scores improved over the course of the study for each device group. Between group comparisons were performed to examine differences in mean scores at each interval. RESULTS: Before receiving their multichannel devices, the two groups of subjects demonstrated similar imitative vowel production skills. After an average of 1.8 yr of device use, the cochlear implant subjects demonstrated significantly improved production of diphthongs and all vowel categories except low vowels. The Tactaid 7 subjects demonstrated significant improvement only in the production of diphthongs. Thus, cochlear implant recipients' vowel production skills were found to be significantly better than those of the Tactaid 7 users after a comparable amount of device experience. CONCLUSIONS: The vowel production gains of the cochlear implant subjects were similar in amount to those noted in other studies of children who use the Nucleus multichannel cochlear implant and further confirm the potential of this device for improved speech production in prelingually deafened children. The differences between the performance of the two groups demonstrate that vowel production skills improved to a greater degree through use of a multichannel cochlear implant than through use of the Tactaid 7.