Graeme Clark Collection
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ItemContributing factors to improved speech perception in children using the nucleus 22-channel cochlear prosthesis( 1997)It has been established that use of multiple-channel intracochlear implants can significantly improve speech perception for postlinguistically deafened adults. In the development of the Nucleus 22-channel cochlear implant, there have been significant developments in speech processing strategies, providing additional benefits to speech perception for users. This has recently culminated in the release of the Speak speech processing strategy, developed from research at the University of Melbourne. The Speak strategy employs 20 programmable bandpass filters which are scanned at an adaptive rate, with the largest outputs of these filters presented to up to ten stimulation channels along the electrode array. Comparative studies of the Speak processing strategy (in the Nucleus Spectra-22 speech processor), with the previously-used Multipeak (Multipeak) speech processing strategy (in the Minisystem-22 speech processor), with profoundly deaf adult cochlear implant users have shown that the Speak processing strategy provides a significant benefit to adult users both in quiet situations and particularly in the presence of background noise. Since the first implantation of the Nucleus device in a profoundly hearing-impaired child in Melbourne in 1985, there has been a rapid growth in the number of children using this device. Studies of cochlear implant benefits for children using the Nucleus 22-channel cochlear implant have also shown that children can obtain significant benefits to speech perception, speech production and language, including open-set understanding of words and sentences using the cochlear implant alone. In evaluating contributing factors to speech perception benefits available for children, four specific factors are important to investigate: (1) earlier implantation -resulting from earlier detection of deafness; (2) improved hardware and surgical techniques -allowing implantation in infants; (3) improved speech processing, and (4) improved habilitation techniques. Results reported previously have been recorded primarily for children using the Multipeak strategy implemented in the MSP speech processor. While it is important to evaluate the factors which might contribute to improvements in speech perception benefits, an important question is the effect of improved speech processing strategy, since this will determine what is perceived through the device. Given that adult patients changing to the Spectra speech processor had also shown improved perception in noisy situations, and the fact that children are in general in noisy environments in the classroom setting for a large proportion of their day, it was of obvious interest to evaluate the potential for benefit in poor signal-to-noise ratios from use of the Speak processing strategy and from specific training in the ability to perceive in background noise. The study was aimed at evaluating whether children who were experienced in use of the Multipeak speech processing strategy would be able to changeover to the new Speak processing strategy, which provides a subjectively different output. Secondly, the study aimed to evaluate the benefits which might accrue to children from use of controlled habilitation in background noise.
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ItemIntroduction(Singular Publishing, 1997)From the time single-channel cochlear implants were first implanted in children in the early 1980s in Los Angeles (Laxford et al 1987) closely followed in 1985 by the multiple-channel cochlear implant in Melbourne (Clark et al 1987a, 1987b) there has been a considerable expansion in the work to apply the multiple-channel cochlear implant to infants and young children.
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ItemEthical issues(Singular Publishing, 1997)The ethics of cochlear implantation in infants and children is an important issue which has received a lot of attention, in particular from the signing deaf community and their advocates. Many of the issues raised by the signing deaf community are in regard to human experimentation and are therefore ethical in nature. Others are concerned with whether it is natural to have a hearing loss, and this goes beyond the realm of ethics. This chapter examines cochlear implantation in children in light of generally accepted ethical principles.
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ItemComponents of a rehabilitation programme for young children using the multichannel cochlear implant(Whurr, 1996)Rehabilitation with young hearing-impaired children may be defined as a teaching; learning process where the role of the clinician is to facilitate acquisition of listening, speech and language in a normal developmental order. This is often referred to as habilitation. It differs from rehabilitation for adults, which is the process by which lost communication skills are reacquired. It is worth discussing the role of the cochlear implant as a tool in this process. For the adult with acquired hearing loss, the cochlear implant might be expected, in part, to facilitate rehabilitation by restoring the auditory sense. The aim is to facilitate speech reception and provide the adult with a speech feedback loop. For a child receiving the cochlear implant, the aims are more complex. The device needs to provide speech perception abilities to facilitate the development of the entire linguistic system, to develop a range of speech sounds, to enable speech monitoring via auditory feedback and to access shared knowledge of the world. (From Introduction)
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ItemSpeech perception for adults using cochlear implants(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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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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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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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 tracking: verfahrensweise und ergebnisse(Springer-Verlag, 1987)Das Speech Tracking wurde im Jahre 1978 von De Filippo und Scott als Schulungs-und Untersuchungsverfahren fur Einzelpersonen eingefuhrt, die weitgehend oder vollstandig ertaubt waren. Bei diesem Verfahren werden dem Patienten Textpassagen von zwei bis zehn Wortern vorgelesen. Der Zuhorende, in diesem Fall der Cochlear Implant-Trager, versucht die betroffene Passage wortlich zu wiederholen. Versteht der Patient eines der Worter nicht, so wendet der Vorleser Verfahren an, die dem Zuhorenden weitere Informationen uber den Inhalt vermitteln. Nachdem jedes Wort korrekt wiederholt worden ist, wird eine weitere Passage vorgelesen, bis ein Prufungszeitraum von 10 Minuten abgeschlossen ist (Martin et al. 1981, 1985; Chouard et al. 1983; Tong et al. 1980; Mecklenburg et al. 1984; Rosen et al. 1980).