Graeme Clark Collection
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ItemSpeech processor design for a multiple-channel cochlear implant( 1980)This paper outlines the strategy adopted for a laboratory-based speech processor used to provide speech information to patients with a multiple-channel cochlear implant It also presents the results of vowel and consonant recognition studies and speech test using open sets of words and sentences.
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ItemA clinical report on speech production of cochlear implant users [Abstract]( 1994)Speech production results are reported for a group of 15 children, adolescents and prelinguistically deafened adults implanted with the 22-electrode cochlear implant. Age at implantation ranged from 5 years to 20 years and implant experience ranged from 1 year to 4 years, 7 months. On a speech intelligibility test using sentences seven implant users improved significantly over time. Mean group performance (n = 11) improved from 18% preoperatively to 43% postoperatively. Similarly on a test of articulation, eight implant users improved significantly over time and the group mean postoperative performance (n = 11) exceeded the preoperative performance (55% compared to 38%). This group effect was significant for consonants and blends but was nonsignificant for vowels. Improvements occurred for front, middle and back consonants, for stops, nasals, fricatives and glides and for voiceless and voiced consonants. Three implant users showed no significant gain on either test. The results suggest complex relationships between speech production performance and sensory information provided by a multichannel implant.
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ItemPitch perception for different modes of stimulation using the Cochlear multiple-electrode prosthesis( 1994)Abstract not available due to copyright.
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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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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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ItemPsychophysical studies using a multiple-electrode cochlear implant in patients who were deafened early in life.( 1992)Psychophysical studies were conducted on 10 cochlear implant patients, between 5 and 23 years of age at the time of surgery, who were deafened prior to 4 years of age. The multiple-electrode prosthesis manufactured by Cochlear Ltd. was used. Identification studies, the recognition of 2-4 stimuli after some training, were conducted on 3 of the 10 patients. For currentlevel and repetition rate identification, performance was comparable to that observed for postlingual adult patients. For electrode position identification, however, performance was much poorer than that observed for postlingual adults. In general, the difference limens for current level, repetition rate and duration, and the gap detection thresholds were similar to those observed for postlingual adults. For 3 patients whose etiology was Usher's syndrome, the repetition rate limens at higher rates were larger than those of the other patients. The limens for electrode position, measured in a discrimination task, were 1-3 electrodes for most patients. However, for 3 patients, limens of 6-10 electrodes were recorded. For numerosity judgements, the counting of stimuli in a temporal series as a function of the rate of presentation, the patients were less successful at counting for rates of 3-8/s than for lower rates (1-2/s).
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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 Ply 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 13:11to 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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ItemSpeech perception results in children using the 22-electrode cochlear implant [Abstract]( 1990)Twenty-one profoundly hearing impaired children ranging in age from 3 to 20 years have been implanted with the 22-electrode cochlear implant (Cochlear Pty ltd) at the University of Melbourne Cochlear Implant Clinic. Five children (aged 6.0 to 14.8 years) 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 five children were implanted during preadolescence and the fifth who had a progressive loss, was implanted during adolescence. Eight children (aged 3.0 to 11 years), have either been implanted recently or are too young for detailed assessments. However some have shown using closed set speech perception tests or vowel imitation tasks, that they are beginning to use the auditory input provided by the implant. The remaining children (aged 13.11 to 20.1 years) have not demonstrated open set recognition but are all full time users of the device. This group was implanted during adolescence after a long duration of profound deafness. The results will be discussed with reference to a number of variables which may contribute to successful implant use; such as age of onset of deafness, duration of deafness. age of implantation, educational program and type of training.
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ItemDiscrimination of electrical trajectories by cochlear implant patients [Abstract]( 1990)Abstract not available due to copyright.
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ItemResults in children using the 22 electrode cochlear implant [Abstract]( 1989)Abstract not available due to copyright.