Graeme Clark Collection

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    Initial results for six patients with a multiple-channel cochlear prosthesis
    Dowell, R. C. ; Brown, A. M. ; Seligman, P. M. ; Clark, Graeme M. (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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    Adults with a severe-to-profound hearing impairment: investigating the effects of linguistic context on speech perception
    Flynn, Mark C. ; Dowell, Richard C. ; Clark, Graeme M. ( 1998)
    Linguistic context is known to influence speech perception abilities in adults with normal hearing. Recent reports question the importance of context for adults with a severe-to-profound hearing impairment. The severe reduction and distortion in acoustic input may result in the listener perceiving insufficient acoustic-phonetic cues to allow access to higher level linguistic processing. To investigate this further, a detailed study of the speech recognition of adults with a severe-to-profound hearing impairment (N=34) was undertaken. A series of aided speech recognition tasks, sequentially examined the different levels of processing in the speech perception chain. The investigation concluded that the effects of severe-to-profound hearing impairment did not reduce the listener's ability to take advantage of contextual cues. There was, however, wide variability between participants in the utilisation of contextual processing. This indicates that to estimate "real-life" speech perception skills, an evaluation of contextual processing ability is required.
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    Evoked potential assessment of children with severe/profound hearing loss: a comparison of steady-state evoked potential (SSEP) and behavioural hearing threshold levels in subjects with absent click evoked auditory brainstem responses (ABR)
    Rance, G. ; Dowell, Richard, C. ; Rickards, F. W. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    Steady-state evoked potential testing offers a means of obtaining accurate, frequency specific estimates of hearing threshold in subjects with even severe to total hearing losses. As such, the technique can play an important role in the preoperative evaluation of young cochlear implant candidates.
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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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    Speech perception of hearing aid users versus cochlear implantees
    Flynn, Mark C. ; Dowell, Richard, C. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    Recent improvements in speech recognition abilities for profoundly deaf cochlear implantees suggests that some adults with a severe hearing impairment might benefit from a cochlear implant. Unfortunately, no studies have directly compared the speech perception abilities of the severely hearing impaired with those of cochlear implant users. An investigation of the speech perception performance of people with a severe hearing loss, who use hearing aids, was conducted in the Department of Otolaryngology at The University of Melbourne. Each participant (n=35) took part in a series of speech perception tests which included 11 vowel recognition tests, CNC words, CUNY sentences, and the Connected Speech Test. The results from these severely hearing impaired persons were compared to results from cochlear implant users. The group of severely hearing impaired adults performed better on tests of vowel and word perception but poorer on tests of open set sentence perception in comparison to a group of cochlear implant users.
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    Rehabilitation strategies for adult cochlear implant users
    Dowell, R. C. ; Blamey, P. J. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    This paper summarizes open-set speech perception results using audition alone for a large group of adult Nucleus cochlear implant users in Melbourne. The results show wide variation in performance but significant improvement over the years from 1982 to 1995. Analysis of these results shows that speech processor developments have made the major contribution to this improvement over this time. Recent results for patients using the SPECTRA-SPEAK processor show !hat most subjects obtain good speech perception within six months of implantation and the need for intensive auditory training is minimal for many of these patients. Postoperative care should encourage consistent device use by providing opportunities for success and providing long term technical support for implant users. In some cases, including elderly patients, those with long term profound deafness, and those with special needs, there will still be a need for additional rehabilitation and auditory training support.
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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.
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    Multicenter evaluations of speech perception in adults and children with the nucleus (cochlear) 22-channel cochlear implant
    Clark, Graeme M. ; Dowell, Richard C. ; Cowan, Robert S. ; Pyman, Brian C. ; Webb, Robert L. (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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    Hearing restoration with the multichannel auditory brainstem implant [Abstract]
    Briggs, R. J. S. ; Kaye, A. H. ; Dowell, R. C. ; Hollow, R. ; Clark, Graeme M. ( 1996)
    Restoration of useful hearing is new possible in patients with bilateral acoustic neuromas by direct electrical stimulation of the cochlear nucleus.
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    Steady state evoked potentials (SSEPs): An objective measure of residual hearing in young cochlear imlpant candidates
    Rance, G. ; Rickards, F. W. ; Dowell, R. C. ; Cohen, L. T. ; Clark, Graeme M. ( 1993)
    The use of objective measures of residual hearing in young cochlear implant candidates has become more important as the minimum age of implantation has reduced. This paper examines the use of the steady-state evoked potential (SSEP) technique in the assessment of these children. SSEP thresholds were obtained using frequency specific stimuli at octave frequencies between 250llz and 4000Hz in ZS children with moderate to severe hearing losses. These levels, determined automatically by a computerized detection system were then compared with thresholds obtained behaviourally. Data was also collected from a group of 35 adult subjects with varying degrees of sensorineural hearing loss. Results indicate that the steady-state evoked potential procedure can provide accurate, frequency specific estimates of hearing thresholds in ears with even profound or total hearing losses.