Graeme Clark Collection
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ItemShort-term auditory memory in children using cochlear implants and its relevance to receptive language [Abstract]( 2000)Current work indicates that many children using cochlear implants are able to hear fine differences between speech sounds but are not progressing as wel1 as expected in receptive language ability. There is anecdotal evidence from teachers that some children using cochlear implants have poor short-term auditory memory ability, which may be impeding their language development. Temporal ordering and short-term memory storage capacity involve higher order processing. Severe auditory deprivation prior to implantation may have caused auditory processing deficits at a cortical level. This study aims to assess short-term, sequential, auditory memory ability in children using cochlear implants and to determine the relationship between this ability and receptive language ability. Short-term auditory memory ability has not been previously investigated in profoundly deaf children using hearing aids and/or cochlear implants. Twenty-four children using the 22-electrode cochlear implant were tested on five short-term sequential memory tasks, three with auditory stimuli and two with visual stimuli. There were 8 children in each of the age groups; 5-6 years, 7-8 years, and 9-11 years. Twenty-four age-matched, normally hearing children served as a control group. Al1 children were also assessed on the receptive subtests of the CELF (Clinical Evaluation of Language Fundamentals) and on the nonverbal scale of the Kaufman Assessment Battery for Children (K-ABC) which measures nonverbal intelligence. This study assessed short-term auditory memory with tasks that required minimal language ability. Prior to the memory tasks, the child had to demonstrate accurate identification of the stimuli with a similar reaction time to the normally hearing controls. As expected there is a significant effect of age on memory performance for the 24 normally hearing children, with older children performing better than the younger children. The memory performance of the children using cochlear implants is therefore described in terms of its deviation from expected performance for a given chronological age. Preliminary results suggest that it is unlikely that auditory deprivation causes a memory deficit specific to the auditory modality. Performance on visual memory tasks is very similar to performance on analogous auditory memory tasks for a group of implant users. The performance of children using cochlear implants on a variety of memory tasks does not appear to be significantly different to that of normally hearing children who are of similar age and nonverbal intel1igence. In contrast their receptive language scores are substantially inferior.
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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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ItemPreoperative residual hearing as a predictor of postoperative speech scores for adult cochlear implant users [Abstract]( 1994)The development of multiple channel cochlear implants has been a significant advance in the rehabilitation of profound hearing loss. Speech perception benefits have been particularly evident for postlinguistically deafened adults, who as a group have shown not only supplementation of lipreading scores but also significant comprehension of words and sentences using an implant alone, without the aid of lipreading. In many cases, patients are able to use their implant for telephone conversation. Speech perception benefits for adult users have increased with advances in speech processing and improved means of habilitation. These improvements in open-set speech benefits for adult users have resulted in a steady increase in group mean scores and a reevaluation of selection criteria for cochlear implantation. In the initial development of cochlear implants, only those with little or no residual hearing were considered as candidates. Current selection criteria now include those with substantial residual hearing, who may score up to 40% in the best-aided condition on word and sentence speech perception tests. In order to provide realistic expectations for prospective cochlear implant patients, it is important to establish the relationship of many preimplant factors to postimplant speech perception benefits. For severely hearing impaired adults, the relationship between preoperative residual hearing, as measured by aided word and sentence speech perception test scores, and postoperative speech perception benefits is of significant interest. Analysis of data collected over a 15 year period for adult patients is presented. The rationale for conducting full speech perception assessments for all potential cochlear implant patients is stressed.
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ItemA clinical report on vocabulary skills in cochlear implant users [Abstract]( 1994)Receptive vocabulary results are reported for 32 children, adolescents and prelinguistically deafened adults implanted with the 22-electrode cochlear implant at the Melbourne Cochlear Implant Clinic. Age at implantation ranged from 2 years, 6 months to 20 years and implant use ranged from 1 year to 7 years, 8 months. There were significant gains from pre- to postoperative assessments on the Peabody Picture Vocabulary Test (PPVT) for the majority of subjects. Rates of improvement found are compatible with previous reports on smaller numbers of implant users, but cannot be attributable unambiguously to use of the implant. The group postoperative performance was significantly higher than mean preoperative performance (n =25). The relationship of variables such as duration of implant use, duration of profound deafness and speech perception ability to improvement on the PPVT is discussed. Expressive vocabulary results on the Renfrew Word Finding Vocabulary Scale are reported for 11 of the subjects. Less substantial gains were made on this measure.
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ItemThe evolution continues: the clinical trials of the SPEAK strategy in Nucleus 22 channel cochlear implant users [Abstract]( 1994)Research in the field of cochlear implants continues in centres around the world. The aim of all centres is to improve the speech perception abilities of those children and adults fitted with a cochlear implant. Most recently the work of Hugh McDermott and Colette McKay (Melbourne University, Department of Otolaryngology) in developing and researching the SMSP (Spectral Maxima Sound Processor) has greatly enhanced the speech understanding abilities of a number of subjects implanted with the Nucleus 22 Channel Cochlear Implant.
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ItemStudies in tactile speech perception using the University of Melbourne Tickle Talker [Abstract]( 1998)During the past four years, a series of studies have been undertaken investigating the perception of speech presented through the tactile modality. These studies formed part of a project to develop an effective and safe electro tactile speech perception device for those children and adults requiring additional communication assistance to that provided by hearing aids, but unable to benefit from cochlear implants.