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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ItemHabilitation issues in the management of children using the cochlear multiple-channel cochlear prosthesis(Wien, 1994)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-impairments, a wide-range of 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 of 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 of 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 setting will have a bearing on the integration of listening and device use into the classroom environment.
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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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ItemPerception of multiple electrode stimulus patterns: implications for design of an electrotactile speech processor( 1991)Abstract not available due to copyright.
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ItemThe Tickle Talker: a speech perception aid for profoundly hearing impaired children [Abstract]( 1990)Fifteen prelingually profoundly hearing-impaired children participated in speech perception training and evaluation, to assess potential benefits from use of the Tickle Talker. This device, a multichannel electrotactile speech processor, developed by Cochlear Pty. Ltd. and the University of Melbourne, presents speech as a pattern of electrical sensations felt on the fingers. The eight small electrodes are located over the digital nerve bundles, on both sides of the four fingers of the non-dominant hand. Speech processing hardware is similar to that used in the 22-channel cochlear implant. In the encoding strategy, second formant frequency (F2) is presented as electrode position, speech waveform amplitude as stimulus strength, and fundamental frequency (FO) as rate of stimulation. Each child participated in an ongoing training program involving clinicians, teachers and parents. The evaluation program included measures of sound and speech detection thresholds, and discrimination of speech features, words and open-set sentences. Both individual and mean scores for all the children demonstrate significant improvements in speech perception scores when input from the Tickle Talker is combined with either aided-residual hearing, or aided residual hearing and lipreading. These results are consistent with those previously reported for profoundly hearing-impaired adults using the Tickle Talker, and indicate that children are able to integrate speech information provided through the tactual modality with information from vision or residual hearing.
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ItemPerception of sentences, words, and speech features by profoundly hearing-impaired children using a multichannel electrotactile speech processor( 1990)Abstract not available due to copyright.
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ItemSpeech perception and spoken language in children with impaired hearing( 1998)Fifty seven children with impaired hearing aged 4-12 years were evaluated with speech perception and language measures as the first stage of a longitudinal study. The Clinical Evaluation of Language Fundamentals (CELF) and Peabody Picture Vocabulary Test (PPVT) were used to evaluate the children's spoken language. Regression analyses indicated that scores on both tests were significantly correlated with chronological age, but delayed relative to children with normal hearing. Performance increased at 45% of the rate expected for children with normal hearing for the CELF, and 62% for the PPVT. Perception scores were not significantly correlated with chronological age, but were highly correlated with results on the PPVT and CELF. The data suggest a complex relationship whereby hearing impairment reduces speech perception, which slows language development, which has a further adverse effect on speech perception.
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ItemThe effect of language knowledge on speech perception: what are we really assessing? [Abstract]( 1996)It is a common finding that many hearing-impaired children have poorer language skills than their normally-hearing peers of the same age. It is also logical to assume that the measurement of open-set speech perception in children with cochlear implants could be affected by limited receptive vocabulary and syntactic knowledge. Therefore, we may be significantly underestimating the speech perception abilities of some hearing-impaired children.
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ItemSpeech perception in children following habilitation with background noise [Abstract]( 1996)Recent evaluation of open-set work and sentence perception results for a group of children evaluated over a two year period showed that improvements to speech perception scores in poor signal-to-noise conditions were possible with use of the Speak speech processing strategy. The increases were noted particularly in speech perception in poor signal-to-noise conditions. However, overall scores were still lower that for hearing in quiet. As children are often in noisy environments, it was of interest to assess whether specific habilitation involving perception in controlled background noise could improve perception. A preliminary study evaluating perception of open-set words and sentences in background noise for four children has been completed. Each of the children was assessed over a six month period, using repeated assessments of connected discourse tracking, and word and sentence perception scores. At each assessment, measures were made both in quiet and in background noise. The specific signal-to-noise ration varied with each child, but was kept constant through the evaluation. During the six month period, children had weekly habilitation sessions, which included specific perceptual training in controlled background noise. Preliminary results indicate that training in ‘controlled noise’ can significantly improve speech perception results for this group of children.