Section A is a review of the literature on the psychological and social implications of cochlear implants (CIs) in deaf children and adolescents. The literature is critically evaluated in relation to health-related quality of life, quality of life, psychological and emotional well-being, social well-being and identity. Relevant theories are outlined and discussed. Methodological limitations and gaps in the literature are discussed, and the review concludes with recommendations for further research. Section B describes a study using Interpretative Phenomenological Analysis to explore adolescent experiences of receiving and living with sequential cochlear implants (SCIs). Semi-structured interviews were conducted with eleven adolescents. The master and sub-themes are presented and the results are discussed with consideration of previous research findings and theoretical, clinical and research implications. Most participants enjoyed improved confidence and social well-being following their SCI, and felt that two CIs were superior to one. The majority identified themselves as hearing and deaf, but not culturally Deaf, as they strived to live in the hearing world. However, this was not without challenges and many young people experienced feelings of difference in the hearing world. These findings have clinical implications in terms of the role of clinical psychologists in CI clinics, and in providing information to families making decisions about CIs. These findings add to the emergent deaf identity development literature in young people with CIs.

(Uncorrected OCR) Abstract of dissertation entitled Tone Perception Performance of Cantonese-speaking Prelingually Deaf Children with Cochlear Implants submitted by Angela On-Chi Wong for the degree of Master of Sciences in Audiology at the University of Hong Kong in May 2000 The present study was a preliminary investigation on the tone perception performance of pre lingually hearing-impaired children with cochlear implant. Seventeen native Cantonese-speaking participants were invited in this research. They have been using the Nucleus multichannel cochlear implant with coding strategy of either SPEAK or ACE. Errors from the tone discrimination and the tone identification tests were examined and a tone confusion matrix was plotted. Results revealed that the correct scores for both discrimination and identification tests were slightly above chance levels, indicating that prelingually hearing-impaired children using cochlear implants were able to benefit from SPEAK or ACE strategies for Cantonese tone perception, though the benefit was small. Tonal error and confusion patterns were discussed and some contributing possibilities were suggested. Relationships between tone perception VII performance and other variables such as age at implantation, duration of implantation, frequency of training and overall auditory performance were also examined. The paper also discussed other possibilities that may contribute to tone confusion. VIII / abstract / toc / Speech and Hearing Sciences / Master / Master of Science in Audiology

Users of cochlear implants typically have difficulty differentiating talkers, identifying vocal expressions of emotion, and recognizing familiar melodies because of the degraded spectral cues provided by conventional implants. This thesis examined these abilities in a small, relatively privileged sample of young bilateral implant users. In Study 1 child implant users and a control sample of hearing children were required to judge whether various utterances were produced by a man, woman, or girl (Experiment 1) and to identify the voices of cartoon characters from familiar television programs (Experiment 2). Child implant users’ performance on talker classification was comparable to that of hearing children. Their identification of cartoon characters’ voices was less accurate than that of hearing children but well above chance levels. These findings challenge conventional wisdom about the talker identification difficulties of implant users. In Study 2 the children were required to indicate whether semantically neutral utterances (Experiment 1) or classical piano excerpts (Experiment 2) sounded “happy” or “sad”. In both cases, implant users performed less accurately than hearing children but well above chance levels. Although the findings on emotion recognition in music are in line with those of previous research, the findings on emotion in speech are at odds with claims that young implant users are insensitive to vocal affect. In Study 3 the children were required to identify the theme songs from familiar television programs on the basis of combined timing and pitch cues as well as timing or pitch cues alone. Implant users’ performance was comparable to that of hearing children except when the cues were restricted to pitch relations, which resulted in performance at chance levels. The findings suggest that the musical representations of young implanted listeners include precise information about timing and coarser information about pitch. They also demonstrate, for the first time, that children, both implant users and those with normal hearing, can identify familiar music on the basis of timing cues alone. Overall, the findings highlight the importance of timing cues for implant users, the range of individual differences, and habilitation possibilities for the recognition of talkers, emotion, and music.

Speaker identification is a challenge for cochlear implant users because their prosthesis restricts access to the cues that underlie natural voice quality. The present thesis examined speaker recognition in the context of spectrally degraded sentences. The listeners of interest were child implant users who were prelingually deaf as well as hearing children and adults who listened to speech via vocoder simulations of implant processing. Study 1 focused on child implant users' identification of a highly salient speaker—the mother (identified as mother)—and unfamiliar speakers varying in age and gender (identified as man, woman, or girl). In a further experiment, children were required to differentiate their mother's voice from the voices of unfamiliar women. Young hearing children were tested on the same tasks and stimuli. Although child implant users performed more poorly than hearing children overall, they successfully differentiated their mother's voice from other voices. In fact, their performance surpassed expectations based on previous studies of child and adult implant users. Even when natural variations in speaking style were reduced, child implant users successfully identified the speakers. The findings imply that person-specific differences in articulatory style contributed to implanted children's successful performance. Study 2 used vocoder simulations of cochlear implant processing to vary the spectral content of sentences produced by the man, woman, and girl from Study 1. The ability of children (5-7 years and 10-12 years) and adults with normal hearing to identify the speakers was affected by the level of spectral degradation and by the gender of the speaker. Female voices were more difficult to identify than was the man's voice, especially for the younger children. In some respects, hearing individuals' identification of degraded voices was poorer than that of child implant users in Study 1. In a further experiment, hearing children and adults were required to provide verbatim repetitions of spectrally degraded sentences. Their performance on this task greatly exceeded their performance on speaker identification at comparable levels of spectral degradation. The present findings underline the importance of ecologically valid materials and methods when assessing speaker identification, especially in children. Moreover, they raise questions about the efficacy of vocoder models for the study of speaker identification in cochlear implant users.

Speaker identification is a challenge for cochlear implant users because their prosthesis restricts access to the cues that underlie natural voice quality. The present thesis examined speaker recognition in the context of spectrally degraded sentences. The listeners of interest were child implant users who were prelingually deaf as well as hearing children and adults who listened to speech via vocoder simulations of implant processing. Study 1 focused on child implant users' identification of a highly salient speaker—the mother (identified as mother)—and unfamiliar speakers varying in age and gender (identified as man, woman, or girl). In a further experiment, children were required to differentiate their mother's voice from the voices of unfamiliar women. Young hearing children were tested on the same tasks and stimuli. Although child implant users performed more poorly than hearing children overall, they successfully differentiated their mother's voice from other voices. In fact, their performance surpassed expectations based on previous studies of child and adult implant users. Even when natural variations in speaking style were reduced, child implant users successfully identified the speakers. The findings imply that person-specific differences in articulatory style contributed to implanted children's successful performance. Study 2 used vocoder simulations of cochlear implant processing to vary the spectral content of sentences produced by the man, woman, and girl from Study 1. The ability of children (5-7 years and 10-12 years) and adults with normal hearing to identify the speakers was affected by the level of spectral degradation and by the gender of the speaker. Female voices were more difficult to identify than was the man's voice, especially for the younger children. In some respects, hearing individuals' identification of degraded voices was poorer than that of child implant users in Study 1. In a further experiment, hearing children and adults were required to provide verbatim repetitions of spectrally degraded sentences. Their performance on this task greatly exceeded their performance on speaker identification at comparable levels of spectral degradation. The present findings underline the importance of ecologically valid materials and methods when assessing speaker identification, especially in children. Moreover, they raise questions about the efficacy of vocoder models for the study of speaker identification in cochlear implant users.

A clinically-focused music appreciation training program (MATP) was developed for use by recipients of cochlear implants (CI) and wearers of hearing aids (HA). It aimed to enhance listeners’ music appreciation abilities, with a specific focus on timbre and musical style. The MATP was pilot-tested on 17 adult postlingually deafened CI recipients (8 female, 9 male, mean age = 60.2 years) and 13 adult HA users (7 female, 4 male, mean age = 63.9 years), with each device group divided into a control and a training group. The training groups were asked to use the MATP for 30 minutes per day four times a week for 10 weeks. The control groups were asked to continue with their normal listening habits for the same time period. Both the training and control groups were assessed on tests of instrument, ensemble and style identification as well as pleasantness ratings of musical excerpts, before and after the 10-week period. Participants in the training groups also completed a program evaluation questionnaire at the end of the training period. The results showed that the training program significantly improved the quality ratings of CI recipients for ensemble stimuli (p = .034). There were, however, no significant improvements for CI users on the timbre discrimination tasks or quality ratings for single instruments, nor were there any significant improvements for the HA users on any of the discrimination tasks or in their quality ratings. The findings suggest that CI recipients’ quality appraisal can be improved through training, independent of perceptual accuracy. On evaluating the program, the majority of CI and HA trainees reported that the MATP was enjoyable and beneficial in terms of music appreciation. Future directions for continued development of the MATP and testing of its efficacy are discussed.

The aim of the present thesis was to examine possible cognitive consequences of acquired hearing loss and the possible impact of these cognitive consequences on the ability to process spoken language presented through visual speechreading or through a cochlear implant. The main findings of the present thesis can be summarised in the following conclusions: (a) The phonological processing capabilities of individuals who have acquired a severe hearing loss or deafness deteriorate progressively as a function of number of years with a complete or partial auditory deprivation. (b) The observed phonological deterioration is restricted to certain aspects of the phonological system. Specifically, the phonological representations of words in the mental lexicon are of less good quality, whereas the phonological system in verbal working memory is preserved. (c) The deterioration of the phonological representations has a negative effect on the individual's ability to process speech, either presented visually (i.e., speechreading) or through a cochlear implant, as it may impair word recognition processes which involve activation of and discrimination between the phonological representations in the lexicon. (d) Thus, the present research describes an acquired cognitive disability not previously documented in the literature, and contributes to the context of other populations with phonological disabilities by showing that a complete or partial deprivation of auditory speech stimulation in adulthood can give rise to a phonological disability. (e) From a clinical point of view, the results from the present thesis suggest that early cochlear implantation after the onset of an acquired severe hearing loss is an important objective in order to reach a high level of speech understanding with the implant.

This study examined the effects of bilateral and unilateral deafness by measuring cortical auditory evoked potential (CAEP) responses in children at initial stages of bilateral cochlear implant (CI) use. We recorded cortical responses evoked by right and left CI stimulation in 127 children with early onset (< 12 months) deafness, with 72 children receiving the two devices in the same surgery (simultaneously implanted) and 55 children receiving the devices in separate procedures (sequentially implanted). Three different types of responses were identified in children with bilateral CIs. No significant effects of duration of deafness, age at implantation, or duration of unilateral CI use were found on response latencies and amplitudes within each type of cortical response, but there were clear differences in responses types between groups and ears. In the context of these findings, the effects of bilateral and unilateral deafness to the auditory pathways were discussed.

Deafness in early development can alter how the brain responds to sound, compromising the restoration of hearing with cochlear implants. We asked how the naïve brain responds to initial cochlear implant stimulation in children who are deaf. Results indicated large variability in initial responses. Deafness associated with GJB-2 mutations led to more uniformity in cortical responses than other etiologies. Responses associated with GJB-2 mutations were characterized by a response peak with large contributions from temporal and frontal regions of the brain. This response may reflect an early stage of auditory development. By contrast, another response type, typical of normal hearing children, received less contribution from frontal regions. Through consistent cochlear implant use, frontal regions of the brain may not be as strongly recruited. Effects of deafness in early development are heterogeneous, which may reflect differences in etiology of deafness and different stages of auditory development.

This study examined the effects of bilateral and unilateral deafness by measuring cortical auditory evoked potential (CAEP) responses in children at initial stages of bilateral cochlear implant (CI) use. We recorded cortical responses evoked by right and left CI stimulation in 127 children with early onset (< 12 months) deafness, with 72 children receiving the two devices in the same surgery (simultaneously implanted) and 55 children receiving the devices in separate procedures (sequentially implanted). Three different types of responses were identified in children with bilateral CIs. No significant effects of duration of deafness, age at implantation, or duration of unilateral CI use were found on response latencies and amplitudes within each type of cortical response, but there were clear differences in responses types between groups and ears. In the context of these findings, the effects of bilateral and unilateral deafness to the auditory pathways were discussed.