Graeme Clark Collection
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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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ItemVariation in speech perception scores among children with cochlear implants(LIPPINCOTT WILLIAMS & WILKINS, 2001-02)OBJECTIVE: The objective of this study was to identify common factors affecting speech perception scores in children with cochlear implants. DESIGN: Speech perception data for 167 implanted children were collected at two cochlear implant centres in Melbourne and Sydney. The data comprised audition-alone scores on open-set word and sentence tests. Children were selected on the basis that they had a Nucleus 22-electrode cochlear implant. The average age of the children was 5 yr. Information was also collected about 12 factors that may have influenced speech perception scores for each child. Analysis of covariance was used to identify factors that significantly affected speech perception scores. Pearson pairwise correlation coefficients were also calculated for all factors analyzed. RESULTS: The analyses in this study identified factors that accounted for 51%, 34%, and 45% of the variance in phoneme, word and sentence perception scores. Scores decreased by 1.4 to 2.4% per year of profound deafness prior to implantation. Children who normally use oral communication scored significantly higher than children normally using sign or simultaneous oral and sign communication. Children implanted in Sydney scored higher on average than children implanted in Melbourne. CONCLUSIONS: The results show that a significant part of the variation in speech perception scores is systematically related to audiological and environmental factors for each child. The reasons for significant differences between children using different communication modes or from different clinics were not identified.
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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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ItemSpeech processing for cochlear implants(JAI Press Ltd, 1992)The cochlear implant is a hearing prosthesis designed to replace the function of the ear. The operation of the prosthesis can be described as a sequence of four functions: the processing of the acoustic signal received by a microphone; the transfer of the processed signal through the skin; the creation of neural activity in the auditory nerve; and the integration of the experience of this neural activity into the perceptual and cognitive processing of the implantee.
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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 Pty 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 13:11 to 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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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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ItemLatest results for adults & children using cochlear implants & future implications( 2000)The overall success of a cochlear implant procedure is most often quantified by assessing how well implantees can understand speech. This is because a primary aim of the application of cochlear implants is to improve communication, and it is relatively straightforward to obtain accurate measures of speech recognition. The quality of cochlear implant hearing is not well described by measuring an audiogram, as the detection of sound is similar across all implantees if the device is functioning correctly. A commonly used measure of speech understanding is the CID everyday sentence test where the number of correctly identified words within sentences is assessed. In the early days of cochlear implants, subjects could only recognize a few words without lipreading but the most recent results show average scores of 80% without lipreading for this sentence test, after 6 months of experience with the device.
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ItemClinical comparison of open-set speech perception with MSP and WSPIII speech processors and preliminary results for the new SPEAK processor [Abstracts]( 1993)There are several studies which compare the WSP III (FOIF11F2) and MSP (Multipeak) speech processors for the Nucleus multiple-channel cochlear implant in small, controlled groups of patients. In the present study we were interested in the benefits of open set speech perception provided by the MSP over the prior WSP III speech processor in a large, unselected clinical population.
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ItemFuture developments in speech processing for multichannel cochlear implants in children [Abstract]( 1992)The average speech perception score for adult implant patients is now about 60% on an open-set sentence test without lipreading. This is higher than the scores obtained by many profound and severe-to-profoundly impaired hearing aid users. This suggests that some hearing aid users, particularly those who use a hearing aid in one ear only, could benefit from a cochlear implant. As neither the implant nor the hearing aid will provide perfect speech recognition it is to be expected that this group should obtain maximum benefit by using the hearing aid in one ear together with the implant in the other ear. However, experience with this group of patients has shown that many people find the use of two independent devices unacceptable. Furthermore, perceptual interaction of the acoustic and electrical signals makes it desirable to be able to control the two outputs in a more co-ordinated way than is possible with two independent devices. Consequently, a "bimodal" speech processor has been developed with both acoustic and electrical outputs controlled from the same speech processing unit. Feature coding aspects of the implant processing have been applied to the acoustic signal in such a way as to enhance speech perception with the hearing aid and improve compatibility with the implant. Initial testing with the bimodal aid shows promise to help severely-to-profoundly impaired individuals. The device has also been useful as a research tool to investigate the complex interactions of simultaneous acoustic and electrical stimulation. The Spectral Maxima Sound Processor (SMSP) has also been developed at the University of Melbourne for use with the Nucleus cochlear implant. Studies with adult subjects have shown improved perception of vowels, consonants, words and sentences in quiet and sentences in background noise with the SMSP as compared with the MSP(MULTIPEAK) which is currently supplied for use with this implant. Results for four subjects showed mean scores for open set sentences at a 10 dB signal-to-noise ratio of 78.7% for the SMSP and 50.0% for the MSP. Mean scores for the same group on open set monosyllabic words in quiet were 57.4% for SMSP and 39.9% for MSP. These results suggest that future improvements in speech perception will be possible for children using the Nucleus cochlear implant.
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ItemFactors affecting speech perceptual performance for children using the 22-electrode cochlear prosthesis [Abstract]( 1992)Speech perception results for all 40 children and adolescents implanted with the. Nucleus 22 electrode cochlear prosthesis in Melbourne (as of February 1, 1992) were used to categorize performance for each child into one of six hierarchical groups: 1: detection of speech including high frequencies 2: discrimination of suprasegmental features of speech in addition to 1,3: discrimination and recognition of .vowel sounds in addition to 1 and 2,.4: discrimination arid recognition of consonant sounds in addition to 1, 2 and 3,5: open set speech. recognition with scores less than 20% for unfamiliar material in addition to 1 to 4,6: open set speech recognition with scores greater than 20% for unfamiliar material in addition to 1 to 5, above.All children demonstrated discrimination of suprasegmentals (level 2) and 58% demonstrated some openset speech recognition (levels 5 and 6). The pattern of results suggested that children who can discriminate segmental features of speech tend to achieve open set speech perception after adequate experience with the prosthesis. The performance level, described above, was used as the dependent variable in a multiple regression analysis to assess the effect of various factors on speech perception performance. The duration of profound hearing impairment and the amount of experience with the prosthesis were shown to contribute significantly to the variance, in performance level. A weaker trend was evident (or recently implanted children which may suggest that those' in oral/aural educational settings progress more rapidly, in terms of speech perception, than those in total communication settings. Age at implantation, cause of deafness, hearing levels prior to implantation, and number of electrodes in use, did not contribute significantly. to the variance in speech perception performance for these children. The results showed that all children with less than seven years of profound hearing impairment and with over one year of experience with the prosthesis have achieved some open-set speech recognition. This is an encouraging result as the trend in clinical application of cochlear prostheses has been towards implanting younger children in recent years. If this sample of hearing-impaired children in Melbourne is representative of the general population, we may expect that most implanted young children will ,develop reasonable speech perception skills after adequate experience and training.