Graeme Clark Collection
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ItemCognitive processing in children using cochlear implants: the relationship between visual memory, attention, and executive functions and developing language skills( 2002)We performed this study to determine whether children using a cochlear implant performed differently from age- and gender-matched hearing aid users on 8 neuropsychological measures of visual memory, attention, and executive functioning. The study also examined whether differences in cognitive skills could account for some of the observed variance in speech perception, vocabulary, and language abilities of hearing-impaired children. In contrast to previous studies, our results revealed no significant cognitive differences between children who use a cochlear implant and children who use hearing aids. Partial correlation analysis indicated that the children’s visual memory skills, i.e., their recognition memory, delayed recall, and paired associative learning memory skills, correlated significantly with their language skills. When examined at a significance level of .01, attention and executive functioning skills did not relate to the children’s developing speech perception, vocabulary, or language skills. The results suggested that differences in visual memory skills may account for some of the variance seen in the language abilities of children using implants and children using hearing aids.
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ItemSpeech perception outcomes in older children who use multichannel cochlear implants: Older is not always poorer(ANNALS PUBL CO, 2002-05)Speech perception outcomes for early-deafened children who undergo implantation as teenagers or young adults are generally reported to be poorer than results for young children. It is important to provide appropriate expectations when counseling adolescents and their families to help them make an informed choice regarding cochlear implant surgery. The considerable variation of results in this group makes this process more difficult. This study considered a number of factors in a group of 25 children who underwent implantation in Melbourne between the ages of 8 and 18 years. Each subject completed open-set speech perception testing with Bamford-Kowal-Bench sentences before and after implantation and preoperative language testing with the Peabody Picture Vocabulary Test. Data were collected regarding the type of hearing loss, age at implantation, age at hearing aid fitting, audiometric details, and preoperative and postoperative communication mode. Results were submitted to a stepwise multiple linear regression analysis with postoperative open-set sentence scores as the dependent variables. The analysis suggested that 3 factors have a significant predictive value for speech perception after implantation: preoperative open-set sentence score, duration of profound hearing loss, and equivalent language age. These 3 factors accounted for 66% of the variance in this group. The results of this study suggest that children who have useful speech perception before implantation, and higher age-equivalent scores on language measures, would be expected to do well with a cochlear implant. Consistent with other studies, a shorter duration of profound hearing loss is also advantageous. The mean sentence score for this group, 47%, was not significantly different from the mean result across all children in the Melbourne program.
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ItemSpeech perception in children using cochlear implants: prediction of long-term outcomes.(Informa UK Limited, 2002-03)A group of 102 children using the Nucleus multichannel cochlear implant were assessed for open-set speech perception abilities at six-monthly intervals following implant surgery. The group included a wide range of ages, types of hearing loss, ages at onset of hearing loss, experience with implant use and communication modes. Multivariate analysis indicated that a shorter duration of profound hearing loss, later onset of profound hearing loss, exclusively oral/aural communication and greater experience with the implant were associated with better open-set speech perception. Developmental delay was associated with poorer speech perception and the SPEAK signal coding scheme was shown to provide better speech perception performance than previous signal processors. Results indicated that postoperative speech perception outcomes could be predicted with an accuracy that is clinically useful.
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ItemCochlear implants: a personal scientific journey [Abstract]( 2002)Electrical stimulation of the auditory system to reproduce hearing commenced through academic curiosity, and the hope of helping deaf people. It received direction from neurophysiology, and later psychophysics and speech science. In the 1960s and 1970s there were many questions requiring answers before cochlear implants could become a practical reality. Key concerns were: (1) the cochlea was too complex for electrical stimulation to reproduce the coding of sound; (2) multiple electrodes inserted into the cochlea for the place coding of frequency could damage the auditory nerves to be stimulated; (3) speech was too complex to be reproduced by electrical stimulation; and (4) children born deaf would not develop the appropriate neural connectivity for speech understanding. The first questions were addressed on the experimental animal. Speech research on patients was only possible with the advent of silicon chip technology allowing the development of an implantable receiver-stimulator package. Initial research established proof of principle that connected discourse was possible with multiple electrode stimulation of the auditory nerve in severely and profoundly deaf people. The research has been developed industrially for the benefits to be provided on a widespread basis through clinics worldwide. Further research has resulted in continuing improvements so that the average profoundly deaf person can hear as well as someone with severe hearing loss using a hearing aid. There is still much research required to achieve high fidelity sound, hearing in noise, and totally implantable devices.
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ItemCochlear implants for adults and children(Martin Dunitz, 2002)Cochlear implants which use multiple-electrode speech-processing strategies are now established clinical entity for children and adults, as a result, preoperative selection and (re)habilitation are key issues. It is hard to realize that it was only in the 1960s and 1970s when many scientists and clinicians said that successful cochlear implants were not possible in the foreseeable future. The questions that had to be addressed by a multi disciplinary research effort are discussed, and the solutions achieved from the University of Melbourne's perspective are presented. However, the main aim of this chapter is to focus on preoperative selection, and (re)habilitation, including the results obtained. These issues are discussed primarily with reference to data from the University of Melbourne's Cochlear Implant Clinic at the Royal Victorian Eye and Ear Hospital. As this is a book on audiological medicine only, an overview of surgical principles is presented. The surgical management of the patient is, of course, very important, so for more details the reader is referred elsewhere. Cochlear implantation has also been the subject of quite intense ethical debate, particularly over its use for children. For this reason, a discussion of ethical issues is included. Finally, the chapter concludes with a vision of research in the next Millennium.
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ItemLateral inhibition in ventral cochlear nucleus chopper neurons: contribution to coding of a speech feature [Abstract]( 2002)Lateral inhibition in the auditory system enhances excitatory responses by suppressing off-best frequency (BF) neural activity. Previous work has suggested that lateral inhibition activated by high frequency frication noise associated with stop consonant plays a role in coding voice onset time (VOT), the period between consonant release and onset of the ensuing vowel.
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ItemPost-implant habilitation for children using cochlear implants: effects on long-term outcome( 2002)Most clinicians working in the cochlear implant field advocate a regular habilitation program for young children receiving implants. The development of auditory skills and the incorporation of these skills into language development are thought to be key areas for such programs. Studies of speech perception and language outcomes demonstrate that an educational approach that emphasises spoken language development appears to enhance the results for implanted children. It remains difficult, however, to demonstrate clearly the effect of habilitation objectively and to determine how much individual attention is desirable for each child. This pilot study considered the long term speech perception and language outcomes for two groups of children who received Nucleus cochlear implants in Melbourne. One group (n=17) was identified as receiving regular habilitation from the Melbourne Cochlear Implant Clinic over a four year post-operative period. Another group (n=l1) was identified as receiving very little regular habilitation over the post-operative period. The language and speech perception results for these two groups showed a significant difference in performance on a wide range of measures with the group receiving regular formal habilitation demonstrating better performance on all measures. These groups included only congenitally, profoundly hearing-impaired children and did not differ significantly on mean age at implant or experience at the time of assessment. Further studies are needed to clarify these results on a larger group of children, and to control for additional confounding variables. Nonetheless, these preliminary results provide support for the incorporation of regular long-term habilitation into cochlear implant programs for children.
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ItemPredicting speech perception outcomes for children using multichannel cochlear implants [Abstract]( 2002)The ability to predict outcomes for children who are cochlear implant candidates is most helpful in counselling families and making clinical recommendations. Open-set speech perception results have been collected for all children implanted with the Nucleus device in Melbourne. Speech perception as assessed at six month intervals following implantation. Information wascollected for each child regarding type of hearing loss, duration and age at onset of profound hearing loss, age at implantation, pre and post-implant communication mode, developmental delay, speech coding scheme and implant experience.