Graeme Clark Collection
Permanent URI for this collection
Search Results
1 - 10 of 29
-
ItemThe use of click-ABR and steady state evoked potentials for hearing assessment in young cochlear implant candidates [Abstract]( 1997)The accurate assessment of hearing thresholds in prospective cochlear implant candidates is essential. As the minimum age of implantation has reduced, audiologists have been faced with the complicated task of obtaining precise audiometric information in children whose immaturity may severely restrict the assessment process. Clearly for these young candidates, there is a place for a reliable, objective measure of residual hearing in the pre-operative test battery. This paper examines the degree of accuracy with which the click-ABR and the steady-state evoked potential (SSEP) techniques can provide estimates of hearing level in subjects with several profound hearing loss.
-
ItemCurrent speech perception benefits for adults using the speak strategy with the nucleus 22-channel cochlear implant( 1997)Present day recipients of the Nucleus 22-channel cochlear implant make use of the SPEAK speech processing strategy in the Spectra 22 speech processor. Introduced in 1994, the SPEAK strategy is based upon research conducted at the University of Melbourne and the Bionic Ear Institute. This paper compares the pre-and post-operative speech perception abilities of adults who have used the SPEAK speech processing strategy since the 'start-up' of their cochlear implant system. Data was analysed from open-set sentence and word tests administered pre-operatively and at regular intervals postoperatively. Patients showed significant improvement in their ability to recognise speech, when listening with the cochlear implant without lipreading, within the first two weeks. Mean scores for open-set sentences were 15% preoperatively and 64% two weeks after initial programming.
-
ItemSpeech perception of hearing aid users versus cochlear implantees [Abstract]( 1997)Recent improvements in speech recognition for profoundly deaf, cochlear implant patients have suggested that some people with a severe hearing impairment would be more successful with a cochlear implant than a hearing aid. Unfortunately, no studies have investigated the speech perception of the severely hearing impaired in order compare their speech perception abilities with those of cochlear implant users. To investigate this area further, a detailed investigation of the hearing aid performance of people with a severe hearing loss is being conducted in the Department of Otolaryngology at The University of Melbourne. The range of hearing losses for this study was defined as a pure tone average of greater than 6OdBHL, but no worse than 100dBSPL in the better ear. At present thirty-five (n=35) participants have been involved in this study. Each participant took part in a series of speech perception tests which included 24 consonant recognition, 11 vowel recognition, CNC words, CUNY sentences, and the connected speech test.
-
ItemLong-term speech perception in children with cochlear implants [Abstract]( 1997)Multichannel cochlear implants have been in use with children for over ten years with an acceleration, in recent years, in the number of young children being implanted. Analysis of speech perception results provides one way of measuring the success of implants in children. The desired outcomes in terms of overall benefit may be better assessed by speech production and language measures. However, in terms of the main aim of cochlear implants, it is useful to look at speech perception initially. This represents a measure of auditory ability which can be compared to normal performance and it is auditory ability that cochlear implants attempt to restore. Language and speech production depend on other factors in addition to auditory ability but it is probably a reasonable assumption that good speech perception is a prerequisite for good speech production and oral language. At the University of Melbourne, we have been able to follow the speech perception of implanted children over the long term. Analysis of results has shown that approximately 80% of implanted children of all ages achieve some understanding of openset speech in sentences (BKB sentences) with a mean score of 32% (n=38).
-
ItemSpeech perception in implanted children: effects of preoperative residual hearing and speech processing strategy [Abstract]( 1997)Since the first child was implanted with the Nucleus 22-channel cochlear prosthesis in Melbourne in 1985, the number of implanted children world-wide has rapidly expanded. Over this period, more effective paediatric assessment and management procedures have developed, allowing cochlear implants to be offered to children under the age of 2 years. In addition, a succession of improved speech processing strategies have been implemented in the Nucleus implant system, resulting in increased mean speech perception benefits for implanted adults. Research in the Melbourne and Sydney Cochlear Implant Clinics has also demonstrated that young children can adapt to and benefit from improved speech processing strategies such as the Speak strategy. 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 speech perception benefits to improve over time with advances in speech processing. 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 effect of the level 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 8 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.
-
ItemPre- & post-operative factors affecting speech perception in adult cochlear implant users( 1997)A common feature of published studies of cochlear implantation is a very wide range of performance levels within a group of patients. It is well-established that preoperative factors including duration of deafness, age at implantation, duration of implant use and etiology can have statistically significant effects on speech perception with a cochlear implant, but they do not account for a very high proportion of the variance within groups of implant users. The biological basis for these effects is not well established. For example, it is unclear whether the effect of duration of deafness is due to a decrease in the number of surviving ganglion cells in the cochlea, to the detailed distribution of functional neurons within the cochlea, to degeneration of nerve function at higher auditory centers, to plastic neural effects during deafness, or to a combination of all of these mechanisms. Data for other factors may cast some light on these possibilities.
-
ItemThe auditory cortex and auditory deprivation: experience with cochlear implants in the congenitally deaf [Abstract]( 1995)The primary auditory cortex (AI) exhibits a topographic representation of the organ of Corti in normal hearing animals. Plasticity studies have shown that this orderly representation of frequency can be modified following a restricted hearing loss or by behavioural trainingl,2. Little is known, however, of the effects of a profound hearing loss on AI, although a number of early studies have suggested an enhancement of activity from other modalities3. Knowledge of the functional status of the central auditory pathway in the profoundly deaf, and the ability of these structures to undergo reorganization particularly following long periods of auditory deprivation - are important issues for the clinical management of cochlear implant patients. In this paper we review our recent clinical and experimental experience with cochlear implants in the congenitally deaf.
-
ItemImprovements in speech perception with the Nucleus 22 electrode cochlear prosthesis [Abstract]( 1996)The 22 electrode cochlear prosthesis developed at the University of Melbourne and manufactured by Cochlear Limited has been implanted in more than 13.000 adults and children with profound deafness since 1982. The implanted electronics has remained largely unchanged but there has been continual development of the externally-worn speech processor. The latest advance in speech coding is known as SPEAK and is implemented in the SPECTRA processor. The SPEAK scheme has been used by implanted adults and children since mid-1994.
-
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, 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.
-
ItemSpeech perception benefits for children using the Speak speech processing strategy in quiet and noise [Abstract]( 1995)The Speak speech processing strategy, based on the Spectral Maxima Speech Processor (SMSP) developed at the University of Melbourne, has now been implemented in the Spectra 22 speech processor developed by Cochlear Pty Limited, and clinical trials of both patients changing from the previous Multipeak strategy to Speak and patients starting up with Speak have been conducted. Results in adult patients changing to Speak have shown significant improvements in speech perception in quiet and particularly in background noise as compared with Multipeak.