Graeme Clark Collection
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ItemInitial results for six patients with a multiple-channel cochlear prosthesis(Monash University Press, 1983)A total of eight patients have been assessed with the multi-channel cochlear prosthesis at the University of Melbourne. The first two patients were implanted with a prototype device in 1978 and 1979, and their results with various speech evaluation procedures have been reported and summarized in detail elsewhere (Clark & Tong, 1982). Briefly, these results indicated that some very significant benefit could be obtained for these patients when using the cochlear prosthesis with external speech processing, particularly when using the device in conjunction with lipreading. It was also shown that some significant understanding of speech was possible without lipreading (open-set) for both patients, although this was fairly limited.
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ItemSpeech perception in implanted children: effects of speech processing strategy and residual hearing(Mendoza Editor, 1997)The ability of implanted children to adapt to different speech processing strategies has been demonstrated for the Nucleus implant system. Children previously experienced with the Multipeak speech processing strategy. were able to gain significant improvements in consonant, word and sentence perception using the Speak speech processing strategy. suggesting some degree of neural plasticity in neural-auditory coding. Of 192 implanted children with different degrees of preoperative residual hearing, 65% were found to obtain significant scores on open-set speech materials using electrical stimulation alone. Those children with more residual hearing had a greater probability of achieving open-set understanding and at a minimum level, perceived high frequency consonant information which would not have been available through conventional hearing aids.
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ItemAn extension of the Multipeak speech processing strategy for the MSP/MINI 22 cochlear implant system( 1992)The speech perception of three post-linguistically deaf adults using the Nucleus MSP/Mini System 22 cochlear implant system programmed with a new speech processing strategy, MPEAK+AO. was evaluated. The MPEAK+AO strategy retains all the information of the standard Multipeak speech processing strategy and additionally presents acoustic components below 400Hz to the most-apical electrode. This extra spectral Information may help implantees understand speech, particularly in noise. Since the estimated fundamental frequency is presented as the rate of stimulation at a fixed intracochlear site and is thereby potentially perceived more easily. and the amplitude of the stimulation on the apical electrode, associated with the voice fundamental, Is directly determined from the estimated energy in the relevant spectral region. these coding factors may provide a better representation ot the prosodic information in speech and a more complete auditory feedback signal. The comparison between Multipeak and MPEAK+AO included tests of vowel, consonant and CNC word recognition. Speech materials were presented with both a male and female speaker. Sentence material. presented with background masking noise (four-speaker babble) was also used. The results showed that the new strategy significantly improved the ability of these MSP users to recognise words in open-set sentences in noisy conditions.
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ItemHabilitation issues in the management of children using the cochlear multiple-channel cochlear prosthesis( 1993)Since 1985, a significant proportion of patients seen In the Melbourne cochlear Implant clinic have been children. The children represent a diverse population, with both congenital and acquired hearing-impairment, a wide-range or hearing levels pre-Implant, and an age range from 2 years to 18 years. The habilitation programme developed for the overall group must be flexible enough to be tailored to the Individual needs of each child, and to adapt to the changing needs or children as they progress. Long-term data shows that children are continuing to show Improvements after 5-7 years of device use, particularly In their perception of open-set words and sentences. Habilitation programs must therefore be geared to the long-term needs of children and their families. Both speech perception and speech production need to be addressed In the specific content of the habilitation program for any Individual child. In addition, for young children, the benefits or Improved speech perception should have an Impact on development of speech and language, and the focus of the programme for this age child will reflect this difference In emphasis. Specific materials and approaches will vary for very young children, school-age and teenage children. In addition, educational selling will have a bearing on the Integration of listening and device use Into the classroom environment.
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ItemA new algorithm for voicing detection and voice pitch estimation based on the neocognitron( 1992)Over the last decade cochlear implants have been used increasingly to restore hearing to the profoundly deaf. One of the more widely used implants is the Nucleus multi-electrode implant, developed by the University of Melbourne and Cochlear Pty. Ltd. The speech processor used with this implant is the MSP, programmed with the multipeak strategy. This device incorporates circuits to estimate the fundamental frequency (FO) of speech signals, and to decide whether voicing is present. This paper describes a new FO estimator and voicing detection algorithm based on the neocognitron; a neural network modelled on the retina and early visual system. Performance was compared with that of three other FO estimation algorithms: linear predictive coding (LPC), cepstral analysis and the algorithm used in the Multipeak-MSP processor. For the speech samples tested, the neocognitron performed more reliably than the other three systems. On the basis of these results, this work may be able to provide benefits to existing and future cochlear implant users.
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ItemAdvances with the 22-channel cochlear implant(Kugler & Ghedini, 1988)The Nucleus 22 Channel Cochlear Implant was developed on the basis of work at the University of Melbourne. Between 1967 and 1978, there was extensive research with animals and human temporal bones, especially regarding safety, psychophysics, histopathology and surgical approaches. As a result of this work, it was decided to develop a multi-channel intracochlear implant. The 22 channel implant has been used in more than 500 patients world-wide but there were many steps on the road to this success. Today, over one third of the post-lingually profound, deaf adults implanted with this device have significant speech understanding without lipreading.
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ItemSurgery for multielectrode cochlear implants( 1987)For the surgery of the NUCLEUS Cochlear Implant (CI) in general anaesthesia we use a skin cut beginning at the bottom of the entrance to the outer ear canal, following the posterior circumference to a point nearly 12 o'clock. From here the incision runs superiorly to the tragus until two or three centimetres above the pinna base and in a wide smooth circle in direction to the occiput. The wide circle is necessary to get a distance of about 2 cm away from the package and also to guarantee the blood supply by the occipital artery and by the postauricular artery as well.
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ItemThe histopathology of the human temporal bone following cochlear implantation in a patient: a summary( 1987)The macroscopic and microscopic evaluation of the implanted and unimplanted temporal bones in a patient who had a cochlear prosthesis for 27 months prior to his death from cardiac disease has shown that the device is biocompatible, and does not lead to any significant adverse effects. The cause of deafness was meningitis.