Graeme Clark Collection

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    Potential and limitations of cochlear implants in children
    Dowell, R. C. ; Blamey, P. J. ; Clark, Graeme M. ( 1995)
    Multiple-channel cochlear implants have been in use with children and adolescents for 8 years. The speech perception, speech production, and language of many of these children has been investigated in some detail.l-4 There have been many predictions about factors that may affect the performance of children with implants. For instance, it has been suggested that children with a congenital loss of hearing would not have the same potential to benefit from a cochlear implant as those with an acquired loss. Similarly, it has been suggested that younger children are likely to gain more benefit from a cochlear implant because of the effect of various critical ages for language learning.5 As more results have become available, it has been our observation that the performance of any particular child with a cochlear implant does not appear to follow well-defined rules, and that generalizations about the potential of certain groups of children are likely to encounter many exceptions. We now have a large quantity of results for children using cochlear implants, and it may be possible to determine some of the factors that have a significant effect on performance. This paper will attempt to identify some of these factors by reviewing speech perception results for 100 children implanted with the Nucleus 22-channel cochlear prosthesis in Australia and speech perception results for adult patients. This analysis will use an "information processing" model of a child using a cochlear implant. That is, we will assume that a child will benefit from a cochlear implant in terms of speech perception, production, and language development, if he or she receives a maximal amount of auditory information from the environment, and is able to process this information successfully. This model divides potential limiting or predictive factors into those that affect the information presented to the auditory system (eg, implant technology, surviving auditory neurons) and those that affect the processing of this information (eg, development of central auditory pathways, amount and consistency of auditory input).
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    Speech perception for adults using cochlear implants
    Dowell, Richard C. (Whurr, 1994)
    A mere 16 years ago, the title of this chapter would have created considerable consternation in audiological circles. A high proportion of otologists and audiologists would have wondered, with good reason, about the potential content of such a chapter. In 1977, there were certainly cochlear implants in use with reported benefits, but reliable documentation of any useful speech perception under controlled conditions was difficult to find. The rapid development of cochlear prostheses since that time has led to thousands of profoundly hearing-impaired adults obtaining benefits for speech perception, and there is now no doubt regarding the efficacy of such devices. This chapter will provide a brief overview of this rapid improvement in the speech perception of adult cochlear implant users, consider some of the reasons for this improvement, and discuss some of the factors that may influence speech perception performance for the individual user. (From Introduction)
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    Clinical results for profoundly deaf patients using the 22-elctrode cochlear prosthesis [Abstract]
    Dowell, R. C. ; Clark, Graeme M. ( 1987)
    The 22-electrode cochlear prosthesis developed in Australia by the University of Melbourne and Cochlear Pty. Limited has been in clinical use in Melbourne for five years. Results for 40 postlingually deaf adults have shown significant communication benefit for 90% of patients. Twenty patients (50%) have demonstrated the ability to understand conversational speech without lipreading or visual cues. No electronic or mechanical failures have been observed in any of the implanted devices. There have been no serious medical complications, but psychological disturbance has occurred in two cases. Experience with prelingually deaf adults has indicated that initial hearing responses for this group are not as good as for the postlingually deaf patients. However, improvement over time has been evident with consistent use of the device. Long-term benefit for these patients will depend to a large extent on motivational and social factors. Results for a small number of young deaf children have been encouraging. The age at onset of profound deafness, intelligence, educational management and family support are all important factors affecting the potential benefit of a cochlear implant for a child.