Graeme Clark Collection
Permanent URI for this collection
Search Results
1 - 10 of 29
-
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.
-
ItemThe effect of language knowledge on speech perception: what are we really assessing?( 1997)Objective: The authors examined whether open-set speech perception scores are limited by knowledge of vocabulary and syntax and further considered whether remediation of vocabulary and syntax will increase open-set speech perception scores. Study Design: This was a repeated-measures study design in the setting of a primary (elementary) school for the hearing impaired. Patients: The study population was composed of three hearing-impaired children using Nucleus 22-channel cochlear implant. Intervention: Intervention used was language remediation sessions. Main Outcome Measures: The main outcome measures were assessment of auditory-alone speech perception benefit using open-set words and sentences and assessment of syntactic knowledge using the Test of Syntactic Ability. Outcome measures were applied before and after remediation. Results: Child 1 and child 2 showed a significant postremediation improvement in their overall scores on the Test of Syntactic Ability and in their ability to perceive words learned during remediation. Child I and child 2 also showed a significant improvement in their scores on a modified Bamford-Kowal-Bench open-set sentence test, which specifically targeted grammatical constructs trained in remediation sessions. Conclusions: Remediation of language knowledge deficits significantly improved open-set speech perception for two children, suggesting a need to include language remediation in cochlear implant habilitation programs.
-
ItemSpeech perception results for children with implants with different levels of preoperative residual hearing( 1997)Objective: Many reports have established that hearing-impaired children using the Nucleus 22 channel cochlear implant may show both significant benefits to lipreading and significant scores on open-set words and sentences using electrical stimulation only. These findings have raised questions about whether severely or severely-to-profoundly deaf children should be candidates for cochlear implants. To study this question, postoperative results for implanted children with different levels of preoperative residual hearing were evaluated in terms of speech perception benefits. Study Design/Setting: A retrospective study of the first 117 children, sequentially, to undergo implantation in the Melbourne and Sydney Cochlear Implant Clinics was undertaken. All children had been assessed by and received their implants in a tertiary referral centre. Main Outcome Measures: To assess aided residual hearing, the children were grouped into four categories of hearing on the basis of their aided residual hearing thresholds measured preoperatively. To assess benefits, the scores of children on standard speech perception tests were reviewed. As different tests were used for children with different ages and language skills, children were grouped into categories according to the level of postoperative speech perception benefit. Results: The results showed that children in the higher categories of aided preoperative residual hearing showed significant scores on open-set word and sentence perception tests using the implant alone. For children in lower categories of aided residual hearing, results were variable within the groups. More than 90% of children with implants with aided residual hearing thresholds in the speech range above I kHz achieved open-set understanding of words and sentences. Conclusion: While the results of this preliminary study confirm previous findings of differential outcomes for children with different levels of preoperative residual hearing, they suggest that children with severe to profound hearing impairments should be considered for cochlear implantation.
-
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.
-
ItemDesign fundamentals for electrotactile devices: the Tickle Talker case study(Whurr, 1995)Since the work of Gault in the 1920s, the literature has chronicled the development of numerous tactile devices for use by the hearing impaired in improving communication. Devices have been developed to target improvements in both speech perception and speech production. In each development, the inventors have attempted to encode speech information through stimulation of the intact kinaesthetic system of the individual, as a supplement or replacement for speech input available from the damaged auditory pathway.
-
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.
-
ItemWithin-subject comparison of speech perception benefits with a multiple-channel cochlear implant and tactile device( 1995)In order to adequately advise prospective cochlear implant patients and their families, a clinician must have a good knowledge of the potential for particular individuals to benefit from cochlear implants and other alternatives.
-
ItemSpeech self-monitoring by children using an electrotactile speech processor( 1995)For the profoundly and severely-to-profoundly hearing impaired child, lipreading and hearing aids are not always sufficient to develop adequate speech perception and production skills. Tactile devices have been investigated as a source of supplementary speech information, with most research focusing on speech perception benefits. However, speech production difficulties are also a major issue for these children, and research into tactile devices should include investigation of the option to use them as speech production aids. This paper will present the results from an initial examination of the suitability of one tactile device for speech production monitoring.
-
ItemSpeech perception in children using the advanced Speak speech-processing strategy( 1995)The Speak speech-processing strategy, developed by the University of Melbourne and commercialized by Cochlear Pty Limited for use in the new Spectra 22 speech processor, has been shown to provide improved speech perception for adults in both quiet and noisy situations. The present study evaluated the ability of children experienced in the use of the Multipeak (Mpeak) speech-processing strategy (implemented in the Nucleus Minisystem-22 cochlear implant) to adapt to and benefit from the advanced Speak speech-processing strategy (implemented in the Nucleus Spectra 22 speech processor). Twelve children were assessed using Mpeak and Speak over a period of 8 months. All of the children had over 1 year's previous experience with Mpeak, and all were able to score significantly on open-set word and sentence tests using the cochlear implant alone. Children were assessed with both live-voice and recorded speech materials, including Consonant-Nucleus-Consonant monosyllabic words and Speech Intelligibility Test sentences. Assessments were made in both quiet and in noise. Assessments were made at 3-week intervals to investigate the ability of the children to adapt to the new speech-processing strategy. For most of the children, a significant advantage was evident when using the Speak strategy as compared with Mpeak. For 4 of the children, there was no decrement in speech perception scores immediately following fitting with Speak. Eight of the children showed a small (10% to 20%) decrement in speech perception scores for between 3 and 6 weeks following the changeover to Speak. After 24 weeks' experience with Speak, 11 of the children had shown a steady increase in speech perception scores, with final Speak scores higher than for Mpeak. Only 1 child showed a significant decrement in speech perception with Speak, which did not recover to original Mpeak levels.
-
ItemImproved electrotactile speech processor: Tickle Talker( 1995)The Tickle Talker, an eight-channel electrotactile speech processor, has been developed from continuing research at the University of Melbourne. 'The development of the device has focused on production of reliable speech-processing hardware, design of cosmetically and ergonometrically acceptable electrode transducers, implementation of acute and chronic biomedical studies demonstrating device safety, design and testing of alternative speech-encoding strategies to provide benefit to speech perception and production, and design and testing of appropriate training methods for optimizing benefits. The Tickle Talker has been shown to provide benefits in supplementing lipreading or aided residual hearing for hearing-impaired adults and children. Improvements in speech processing have resulted in an increase in benefits to speech perception, and open the way for more flexible approaches to encoding speech input. Continuing development of the electrode circuitry has now produced a device that is robust and has an extended battery life. Safety studies have clearly demonstrated that there are no long-term contraindications to device use. The results suggest that the device has a role to play in rehabilitation programs for severely and profoundly hearing-impaired adults and children.