Graeme Clark Collection

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    Electrode discrimination and speech perception in young children using cochlear implants
    Dawson, P. W. ; McKay, C. M. ; Busby, P. A. ; Grayden, D. B. ; Clark, Graeme M. ( 2000)
    Objective: The aim was to determine the efficacy of a child-appropriate procedure to assess electrode discrimination ability in young children using cochlear implants and to investigate the relationship of electrode discrimination ability and speech perception performance in children implanted at a young age. Design: An adaptation of the play audiometry procedure was used to assess electrode discrimination in seventeen 4- to 10-yr-old children. The children were required to respond with a game-like motor response when a repeating stimulation on a reference electrode “changed” to a different electrode. They were also assessed on a speech feature discrimination test, a closed-set word recognition test and a nonverbal intelligence task. Results: Sixty-five percent of subjects demonstrated ability to discriminate adjacent electrodes in mid and apical regions of the cochlea, whilst the remaining subjects needed electrode separations of between two and nine electrodes for successful discrimination. In a forward stepwise regression analysis electrode discrimination ability was found to be the strongest factor in accounting for variance in the speech perception scores. Subject variables such as duration of deafness, nonverbal intelligence and implant experience did not significantly account for further variance in the speech perception scores for this group of children. Conclusions: Electrode discrimination ability was the strongest factor in predicting performance on speech perception measures in a group of children using cochlear implants.
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    Training place pitch perception in cochlear implant users [Abstract]
    Dawson, Pam ; Clark, Graeme M. ( 1997)
    The study has aimed at determining whether the ability to use place coded vowel formant information could be enhanced with analytical vowel training in a group of -congenitally deafened patients, who showed limited speech perception skills after cochlear implant experience ranging from 1y8m to 6y11m. It has investigated whether improvements in vowel perception after training can carry over to word recognition. A further objective was to see whether poorer vowel perception was associated with poorer electrode position difference limens. Three children, one adolescent and one young adult were assessed with synthesized versions of the words /hid, head, had, hud, hod, hood/ and a natural version of these words as well as with a closed-set monosyllabic word task. The change in performance after 10 training sessions was compared to the change in performance during a non-training period. Four of the five patients showed a significant gain in synthetic vowel perception post-training on at least one assessment, but only two patients showed gains across a number of tests post-training. For one of these 2 children improvements in vowel perception generalized to word perception. Patients’ electrode limens ranged from 1 to 3 electrodes except for 1 adolescent whose minimal progress post-training could be partly explained by poorer apical electrode discrimination. The findings are discussed with reference to a number of factors, including the notion of a "critical period" for neural plasticity.
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    What factors contribute to successful outcomes for children using cochlear implants
    Cowan, Robert C. ; Clark, Graeme M. ; Dowell, Richard C. ; Dettman, Shani J ; Barker, Elizabeth ; Latus, Katie ; Hollow, Rod ; Blamey, Peter J. ( 2000)
    Long term speech perception data has been collected for 100 children using the Nucleus multichannel cochlear prosthesis in Melbourne. Scores on a number of different assessments are available at approximately six month intervals following implantation for these children. The group represents an unselected sample of cochlear implant users, as all children were included if they had sufficient developmental skills to perform formal speech perception tests. Information was also collected on each child regarding type of hearing loss, age of onset of profound hearing loss, duration of profound hearing loss, age at implantation, pre and post-implant communication mode, developmental delay, speech processing strategy and length of experience with implant use.
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    Application of the cochlear implant to profoundly hearing impaired adolescents: re-visiting the inclusion criterion for older children
    DETTMAN, SHANI ; Latus, Katie ; Cosson, Liz ; Dowell, Richard C. ; Clark, Graeme M. ( 2000)
    Objective: The purpose of this study is to examine the range of outcomes for older children receiving the multi-channel cochlear implant. Recent improvements in the speech perception performance for profoundly hearing impaired children and adults have lead to expanded selection criterion for cochlear implant inclusion. That is, the efficacy of cochlear implants for adults with acquired hearing loss is well documented. In addition, the application of the cochlear implant to young children has lead to improvements in open set speech perception, speech production and language acquisition. In contrast, congenitally deaf and prelingually deafened children who are implanted after the age of 8 years have performed poorer than children implanted at a younger age on speech perception, speech production and psychophysical performance measures.
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    Speech perception in noise with cochlear implant and hearing aid for implanted adolescents
    DETTMAN, SHANI ; Latus, Katie ; Cosson, Liz ; Dowell, Richard C. ; Clark, Graeme M. ( 2000)
    Objective. To describe the open set speech perception performance for 8 congenitally deaf adolescents who use a multichannel cochlear implant and behind-the ear hearing aid as their 'everyday listening' condition. Expanded indication for cochlear implant inclusion has lead to the implantation of a number of persons with severe to profound hearing loss. It has been suggested that persons who have some residual bearing are good candidates for the cochlear implant due to: the presence of more ganglion cells, prior auditory experience, pre-patterning of the auditory cortex or other factors, as yet unknown, such as language experience.
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    The relationship between aetiology of hearing loss and outcome following cochlear implantation in a paediatric population
    O'Sullivan, P. G. ; Ellul, S. M. ; Dowell, B. C. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    Eighty-eight children who underwent cochlear implantation at the University of Melbourne Cochlear Implant Clinic are reviewed. The aetiology of the hearing loss is classified and is compared to their best level of speech perception performance. The group whose hearing loss was not congenital in origin performed better than those who were congenital in origin. Of those whose hearing loss was congenital in nature those with rubella appeared to perform best.
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    Factors affecting outcomes in children with cochlear implants
    Dowell, R. C. ; Blamey, P. J. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    Open-set speech perception tests were completed for a group of 52 children and adolescents who were long-term users of the Nucleus multiple channel cochlear prosthesis. Results showed mean scores for the group of 32.4% for open-set BKE sentences and 48.1% for phonemes in open-set monosyllabic words. Over 80% of the group performed significantly on these tas1cs. Age at implantation was identified as a significant factor affecting speech perception performance with improved scores for children implanted early. This factor was evident in the results at least down to the age of three years. Duration.. of profound hearing loss, progressive hearing loss, educational program and preoperative residual hearing were also identified as significant factors that may affect speech perception performance.