Graeme Clark Collection
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ItemThe effects of electrode position and stimulus period on the hearing sensations in a multiple-channel cochlear implant patient [Abstract]( 1981)Abstract not available due to copyright.
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ItemPerceptual dissimilarity and discrimination studies using two-electrode stimulation with a multiple-channel cochlear implant patient [Abstract]( 1981)Abstract not available due to copyright.
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ItemA multiple-channel cochlear implant: an evaluation using nonsense syllables( 1981)A study using nonsense syllables has shown that a multiple-channel cochlear implant with speech processor is effective in providing information about, voicing and manner and to a lesser extent place distinctions. These distinctions supplement lipreading cues. Furthermore, the average percentage improvements in overall identification scores for multiple-channel electrical stimulation and lipreading compared to lipreading alone were 71% for a laboratory-based speech processor and 122 % for a wearable unit.
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ItemPitch and loudness studies on a multiple-channel cochlear implant patient [Abstract]( 1981)Abstract not available due to copyright.
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ItemSpeech processing for cochlear implants(JAI Press Ltd, 1992)The cochlear implant is a hearing prosthesis designed to replace the function of the ear. The operation of the prosthesis can be described as a sequence of four functions: the processing of the acoustic signal received by a microphone; the transfer of the processed signal through the skin; the creation of neural activity in the auditory nerve; and the integration of the experience of this neural activity into the perceptual and cognitive processing of the implantee.
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ItemResults for children and adolescents using the multichannel cochlear prosthesis [Abstract]( 1992)The first adolescent to use the 22-electrode cochlear prosthesis was Implanted In Melbourne in 1985 and the first child (less than 10 years), the following year. Since then, over 100 children have received the cochlear prosthesis in Australia and over 1200 worldwide. Detailed assessment of 200 children in the U.S.A., Australia and Germany lead to the market approval of the prosthesis by the U.S. Food and Drug Administration in July 1990. The analysis of results for these children has proven to be difficult due to the use of different tests in different places, the lack of appropriate assessment tools for young children, the wide range of performance, and the problems of cooperation for young children. Despite these problems, some trends are beginning to emerge in the speech perception results for implanted children. Children with a greater amount of auditory experience before becoming profoundly deaf tend to perform better, as do children with more experience with the cochlear prosthesis. Those with a greater number of electrodes in use also perform better, a result supported by adult studies. Although older prelinguistically deafened children do not perform as well as postlinguistically deafened adults, there appears to be little difference between results for pre-and post-linguistically deafened young children. These trends In speech perception results will be discussed in more detail.
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ItemCochlear implants in children, adolescents, and prelinguistically deafened adults: speech perception( 1992)A group of 10 children, adolescents, and prelinguistically deafened adults were implanted with the 22-electrode cochlear implant (Cochlear Pty Ltd) at the University of Melbourne Cochlear Implant Clinic and have used the prosthesis for periods from 12 to 65 months. Postoperative performance on the majority of closed-set speech perception tests was significantly greater than chance, and significantly better than preoperative performance for all of the patients. Five of the children have achieved substantial scores on open-set speech tests using hearing without lipreading. Phoneme scores in monosyllabic words ranged from 30% to 72%; word scores in sentences ranged from 26% to 74%. Four of these 5 children were implanted during preadolescence (aged 5:5 to 10:2 years) and the fifth, who had a progressive loss, was implanted during adolescence (aged 14:8 years). The duration of profound deafness before implantation varied from 2 to 8 years. Improvements were also noted over postoperative data collection times for the younger children. The remaining 5 patients who did not demonstrate open-set recognition were implanted after a longer duration of profound deafness (aged 13:11 to 20:1 years). The results are discussed with reference to variables that may affect implant performance, such as age at onset of loss, duration of profound loss, age at implantation, and duration of implantation. They are compared with results for similar groups of children using hearing aids and cochlear implants.
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ItemCochlear implantation for children: an update [Abstract]( 1992)The performance of the Nucleus 22 channel cochlear implant has been assessed on 142 English speaking children who have worn their device for at least 12 months. The safety of the device has been evaluated on 309 children. A significant improvement for prosody was observed in 66%, for closed-set words in 63% and open-set words in 46%, using electrical stimulation alone. Performance over time increased, especially for open-set speech tests. Prelinguistically deaf children had similar scores to postlinguistically deaf children from prosody and closed-set word tests, but scores were not as good for open-set word tests. Lipreading enhancement was assessed using the CID sentence test, and the mean lipreading-alone score of 51% increased significantly to 71% when lipreading was combined with electrical stimulation. Speech intelligibility was determined with McGarr material and 63% were significantly more intelligible after 12 months' implant experience. There were 6-8% medical/surgical complications compared to 12% for a comparable group of adults. In 2.6% surgical intervention was required and this was primarily for infection or necrosis of the flap.
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ItemThe development of the Melbourne/Cochlear multiple-channel cochlear implant for profoundly deaf children( 1992)In 1978-79, a speech processing strategy which extracted the voicing (FO) and second formant (F2) frequencies and presented these as rate and place of stimulation respectively to residual auditory nerve fibres was developed for the University of Melbourne's prototype multiple-channel receiver-stimulator (Clark et aI1977, Clark et a11978, Tong et aI1980). This speech processing strategy was shown to provide post linguistically deaf adults with some open-set speech comprehension using electrical stimulation alone, and considerable help when used in combination with lipreading (Clark et al 1981).
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ItemFactors predicting postoperative sentence scores in postlinguistically deaf adult cochlear implant patients( 1992)A sample of 64 postlinguistically profoundly to totally deaf adult cochlear implant patients were tested without lipreading by means of the Central Institute for the Deaf (CID) sentence test 3 months postoperatively. Preoperative promontory stimulation results (thresholds, gap detection, and frequency discrimination), age, duration of profound deafness, cause of deafness, lipreading ability, postoperative intracochlear thresholds and dynamic ranges for electrical stimulation, depth of insertion of the electrode array into the scala tympani, and number of electrodes in use were considered as possible factors that might be related to the postoperative sentence scores. A multiple regression analysis with stepwise inclusion of independent variables Indicated that good gap detection and frequency discrimination during preoperative promontory testing, larger numbers of electrodes in use, and greater dynamic ranges for intracochlear electrical stimulation were associated with better CID scores. The CID scores tended to decrease with longer periods of profound deafness.