Graeme Clark Collection
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ItemSpeech perception in implanted children: influence of preoperative residual hearing on outcomes [Abstract]( 1998)Since the first child was implanted with the Nucleus 22-channel prosthesis in Melbourne in 1985, several thousand children world-wide have now benefitted from this technology. More effective paediatric assessment and management procedures have now been developed, allowing cochlear implants to be offered to children under the age of 2 years. Improvements in speech processing strategy have also been implemented in the Nucleus implant system, resulting in increased mean speech perception benefits for implanted adults. Although a range of performance on formal measures of hearing, speech or language has been reported for children using implants, results from the first decade of implant experience consistently show that significant benefits are available to children receiving their implant at an early age. Reported speech perception results for implanted children show that a considerable proportion (60%) of paediatric patients in the Melbourne and Sydney clinics are able to understand some open-set speech using electrical stimulation alone. These results, and the upward trend of mean speech perception benefits shown for postlinguistically deafened adults have raised questions as to whether severely, or severely-to-profoundly deaf children currently using hearing aids would in fact benefit more from a cochlear implant. To investigate the potential influence of the degree of preoperative residual hearing on postoperative speech perception, results for all implanted children in the Melbourne and Sydney cochlear implant programs were analysed. Results showed that as a group, children with higher levels of preoperative residual hearing were consistently more likely to achieve open-set speech perception benefits. Potential factors in this finding could be higher levels of ganglion cell survival or greater patterning of the auditory pathways using conventional hearing aids prior to implantation. Conversely, children with the least preoperative residual hearing were less predictable, with some children achieving open-set perception, and others showing more limited closed-set benefits to perception. For these children, it is likely that preoperative residual hearing is of less significance than other factors in outcomes.
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ItemThe progress of children using the multichannel cochlear implant in Melbourne( 1995)Multi-channel cochlear implantation in children began in Australia in 1985 and there are now close to 4000 profoundly deaf children and adolescents using the Australian implant system around the world. The aim of the implant procedure is to provide adequate hearing for speech and language development through auditory input. This contrasts with the situation for adults with acquired deafness where the cochlear implant aims to restore hearing for someone with well-developed auditory processing and language skills. As with adults, results vary over a wide range for children using the Multi-channel implant. Many factors have been suggested that may contribute to differences in speech perception for implanted children. In an attempt to better understand these factors, the speech perception results for children implanted in Melbourne were reviewed and subjected to statistical analysis. This has indicated that the amount of experience with the implant and the length of sensory deprivation are strongly correlated with perceptual results. This means that younger children are likely to perform better with an implant and that a number of years of experience are required for children to reach their full potential. The results have also indicated that educational placement and management play a crucial role in children reaching their potential. Overall, 60% of the children and adolescents in the study have reached a level of open-set speech understanding using the cochlear implant without lipreading.
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ItemVowel imitation task: results over time for 28 cochlear implant children under the age of eight years( 1995)With increasing numbers of implanted children under the age of 4 years, numerous researchers have reminded us of the need for valid, sensitive, and reliable tests of developing speech perception.1,2 In addition to studies of the efficacy of implanted prostheses, there is a need to investigate the many variables that influence children's communicative performance, such as changes in speech-coding strategy, updated speech-processing systems, the effects of various training regimens, and the selection of educational and communication modes.
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ItemCochlear implants in children, adolescents, and prelinguistically deafened adults: speech perception( 1992)A group of 10 children, adolescents, and prelinguistically deafened adults were implanted with the 22-electrode cochlear implant (Cochlear Ply Ltd) at the University of Melbourne Cochlear Implant Clinic and have used the prosthesis for periods from 12 to 65 months. Postoperative performance on the majority of closed-set speech perception tests was significantly greater than chance, and significantly better than preoperative performance for all of the patients. Five of the children have achieved substantial scores on open-set speech tests using hearing without lipreading. Phoneme scores in monosyllabic words ranged from 30% to 72%; word scores in sentences ranged from 26% to 74%. Four of these 5 children were implanted during preadolescence (aged 5:5 to 10:2 years) and the fifth, who had a progressive loss, was implanted during adolescence (aged 14:8 years). The duration of profound deafness before implantation varied from 2 to 8 years. Improvements were also noted over postoperative data collection times for the younger children. The remaining 5 patients who did not demonstrate open-set recognition were implanted after a longer duration of profound deafness (aged 13:11to 20:1 years). The results are discussed with reference to variables that may affect implant performance, such as age at onset of loss, duration of profound loss, age at implantation, and duration of implantation. They are compared with results for similar groups of children using hearing aids and cochlear implants.
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ItemPreliminary speech perception results for children with the 22-electrode Melbourne/ cochlear hearing prosthesis( 1993)The 22-electroce cochlear prosthesis developed by the University of Melbourne and Cochlear Pty. Ltd. has been shown to provide significant speech perception benefits to profoundly deafened adults. More recently, use of an improved Multipeak encoding strategy has significantly improved speech perception performance both in quiet and in noise. Benefits to speech perception in children have not as yet been fully documented, in part due to the shorter history of implant use in children and the smaller overall number of children implanted as compared with adults. The first implantation of the 22-electrode cochlear prosthesis in a child was carried out in Melbourne in January of 1985. In Melbourne, a 5-year-old child was operated on in April 1986, and a first congenitally deaf child in April 1987. The age of implantation has been progressively reduced, with the first 2-year-old child implanted in Melbourne in 1990. As at January 1992, approximately 1,200 children (under 18 years of age inclusive) have been implanted worldwide with the 22-electrode cochlear prosthesis. Of this number, approximately 50% are under the age of 6 years. The age of the child, aetiology of the hearing loss, age at onset and duration of the hearing loss, education program attended both prior to and subsequent to implantation, and parental motivation to assist in habilitation are all factors which may affect an individual child's development and progress with the device. Evaluation of performance in children is complicated by a number of issues, including the effects of delayed speech and language development, and the ability of individual children to perform auditory tests. The measure of performance chosen for any evaluation will also reflect the interests of the particular clinician. For example, effects of device use on speech production may be of interest to the speech therapist, whereas educational progress will be of primary importance to the teacher of an implanted child. However, in choosing an appropriate evaluation test to measure progress woth the cochlear prosthesis, it is vital to realize that all measures such as effects of device use on speech production, educational progress, development of language, and effects on social and communication skills depend on the child being able to accurately perceive speech information through her/his device.
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ItemSpeech perception benefits for implanted children with preoperative residual hearing [Abstract]( 1995)Since the implantation of the first children with the Nucleus 22-channel cochlear prosthesis in Melbourne in 1985, there has been rapid expansion in the number of implanted children world-wide. Improved surgical technique and experience in paediatric assessment and management have contributed to a trend to implant very young children. At the same time there has also been continuing development of improved speech processing strategies resulting in greater speech perception benefits. In the Melbourne program, over 60% of children obtain significant scores on open-set word and sentence tests using their cochlear implant alone without the aid of lipreading. As parents and professionals have become aware of these improved benefits to speech perception benefits in profoundly deaf children, there have been requests to consider implanting severely-to-profoundly deaf children. In these children with higher levels of residual hearing, only those children with poorer-than-expected performance on speech perception tests using hearing aids have been considered for surgery. A number of such cases have now been implanted in the Melbourne program. The speech perception benefits for this group are reported and are being compared with benefits for the profoundly deaf group of children.
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ItemResults of multichannel cochlear implantation in very young children [Abstract]( 1995)Most researchers and clinicians working in the cochlear implant field have assumed that profoundly deaf children will have a better prognosis in terms of speech perception, speech production and language development. if implanted at as young an age as possible. However, it has been difficult to gather direct evidence for this hypothesis due to the problems in assessing children under the age of five years with formal tests. Recent results with older children have supported the view that early implantation may provide the optimal outcome in most cases. The implantation of very young children raises two areas of concern that do not apply in adults and older children: accurate assessment of degree of hearing loss and auditory potential; and postoperative assessment of outcomes. This paper will describe research results from the University of Melbourne which address these issues and present results for children implanted as young as eighteen months of age.
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ItemSpeech perception benefits for children using the 22-channel Melbourne/cochlear hearing prosthesis [Abstract]( 1993)In 1985; the first child was implanted with the Cochlear 22-channel cochlear prosthesis at the University of Melbourne Royal Victorian Eye & Ear Hospital Cochlear Implant Clinic. There are now 42 children who have received the device in Melbourne. Analysis of patient details for these children show a very heterogeneous group, with a wide range in age, hearing thresholds, duration of deafness and aetiology. The major aetiologies found were either a congenital profound deafness.; or a hearing loss due to meningitis. In all but 3 cases, the children are using 15 or more electrodes in the array. Speech perception benefits have been analyzed according to a six-level hierarchical classification scheme. All of-the children achieved a minimum benefit of discrimination of suprasegmental information (Category 2), and 59% of the children achieved open-set understanding of unfamiliar speech material without the aid of lip-reading (Categories 5 & 6). Detailed analysis suggests that the majority of children achieving open-set speech perception benefits had more than one year of experience with their implant. and less than seven years of profound deafness prior to implantation.
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ItemFactors associated with open-set speech perception in children using the Cochlear multiple-channel prosthesis [Abstract]( 1993)Since 1985, nearly 100 children have received the 22-channel cochlear prosthesis from the Melbourne and Sydney cochlear implant clinics. These two clinics account for the bulk of casesin Australia, and have similar management philosophies and selection criteria. The patient population represents a variety of etiologies, and ranges in age from 2 - 18 years of age. Bothcongenital and postlinguistic hearing losses are included. In order to assess benefit to speech perception in such a diverse group, the children's results have been tabulated according to a six level hierarchical scale of speech perception achievement. The scale ranges from category I,detection of sound only, to category 6, which includes significant perception scores for open-setwords and sentences. Analysis of the results shows that the majority of the children are achieving open-set speech perception benefits, and that results continue to improve with additional experience with their devices. There are a number of contributing factors to these open-set speech� perception results which have impact both on selection issues and on habilitation with different age ranges �of patients.