Graeme Clark Collection
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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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ItemMulticenter evaluations of speech perception in adults and children with the nucleus (cochlear) 22-channel cochlear implant(Kugler, 1996)The Nucleus 22-channel cochlear implant has been implanted in over 10,500 patients in 79 countries. and used for more than 25 languages. It arose as a result of our early physiological, behavioral and biological research on experimental animals. The historical development of the Nucleus device has been outlined in detail by Clark. Our ongoing research has led to improvements in the way speech is processed with the 22-channel device that are now resulting in improved speech perception for profoundly totally deaf people that is, on average, better than the speech perception obtained by many deaf people with hearing aids. The multiple-channel cochlear implant was first approved by the US Food and Drug Administration (FDA) for use in postlinguistically deaf adults in 1985. It was subsequently approved for use in children in 1990. The proportion of children (18 years of age and under) to have now received it is approximately 439C (4,500 out of 10.500). In evaluating improvements in speech processing it is important to design well-controlled studies, and a number of important ones which have previously been published are summarized in this paper. In addition, speech perception results for all the Nucleus speech processing strategies have been obtained four to six months postoperatively from unselected patients presenting to the Cochlear Implant Clinic at the Royal Victorian Eye & Ear Hospital (RVEEH), Melbourne, and are presented in this paper. As results can vary greatly with different durations of experience it is essential to make comparisons at the same time postoperatively. These clinical data are the most complete to date for comparing the Nucleus speech processing strategies.
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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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ItemSelection of patients for multiple-channel cochlear implantation(Raven Press, 1985)Only profoundly, bilaterally deaf adults are considered for evaluation. It is necessary to determine that the patient's communication ability cannot be improved to any significant degree with conventional hearing aids currently available. Initial assessment consists of audiometry, hearing aid evaluation(s), otological and medical examination, and for patients with no recent experience with hearing aids, a hearing aid trial. Polytome x-rays of temporal bones is carried out to ensure that cochlea structures are not grossly abnormal. Electrical stimulation of the promontory is used to confirm the presence of residual auditory nerve fibers. Where there is an audiometric difference between ears, the poorer ear is chosen for implantation provided there are no other contraindications. Intensive counselling is carried out to enable patients to make a fully informed decision about implantation. Patients undergo a battery of speech discrimination and lipreading tests with their hearing aid after their hearing aid trial. This is to provide a baseline for comparison with postoperative results and to assess the benefit obtained from the hearing aid. Any significant improvement in test results when using a hearing aid over lipreading alone would be a contraindication for implantation. Medical assessment is carried out as for any major surgery, including pathology, respiratory function tests and cardiovascular assessment. Particular emphasis is placed on infection prevention immediately preoperatively and during surgery.