Graeme Clark Collection
Permanent URI for this collection
Search Results
1 - 10 of 20
-
ItemThe importance of different frequency bands to the speech perception of cochlear implantees [Abstract]( 1996)It is well known that cochlear implantees exhibit a wide range of speech perception ability. Understanding the reason for this variability may lead to improved speech processors. This study investigates whether implantees rely on different areas of the speech spectrum for speech cues, compared to normally hearing listeners, and whether poor performers rely on different spectral areas than better performers. Six subjects with the Mini System 22 implant and using the SPEAK strategy participated in this experiment. Scores for monosyllabic words were obtained using the full speech spectrum and with selected frequency bands removed from the subjects’ speech processor maps. The Articulation Index (AI) is a measure of the proportion of speech information available to a listener, and the relative contribution to AI from different frequency bands is termed the Importance Function. The five frequency bands studied in this experiment were determined to be of equal importance to normally hearing listeners for the speech material used. The scores for each implantee were transformed into AI values, and hence the relative importance of the bands was determined. This relative importance was compared between the implantee group and normally hearing listeners to determine the way in which speech perception by electrical stimulation varies from that by acoustical stimulation. Comparisons were also made between individual implantees to determine whether correlations exist between their speech perception ability and their use of cues in different parts of the spectrum. Further research will determine whether the differences among implantees are correlated with their ability to perceive changes in stimulation place or temporal characteristics.
-
ItemCochlear implants: future research directions( 1995)The future of cochlear implants for profoundly deaf people now seems assured, and further research should improve its benefits. The present benefits of cochlear implants have now been clearly demonstrated. The results have shown that many postlingually deaf adults get significant open-set speech recognition using electrical stimulation alone, and that profoundly deaf children with a cochlear implant get better speech perception than similar children who use hearing aids or tactile vocoders.
-
ItemResearch in auditory training(Academy of Rehabilitative Audiology, 1994)Speech perception and communication can improve as a result of experience, and auditory training is one way of providing experiences that may be beneficial. One of the most important factors influencing the effectiveness of auditory training is the amount of experience the client already has. Other factors include the severity of the hearing loss, the sensory device used, the environment, personal qualities of the client and clinician, the type of training, and the type of evaluation used. Despite a long history of clinical practice, the effects of these factors have been investigated in few controlled studies. Even in special cases where training has an obvious role, such as adults using cochlear implants, there has been little objective comparison of alternative training methods. One reason for this is the difficulty of carrying out definitive experiments that measure changes in performance over time in the presence of many confounding variables. These variables may also help to explain the apparently contradictory results that can be found in the literature on auditory training and in the diverse points of view expressed by practicing clinicians. Issues and methods appropriate for research in auditory training among adult clients are discussed with reference to the needs of modem clinical practice.
-
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.
-
ItemComparison of current speech coding strategies( 1993)This paper reports on two studies carried out at the University of Melbourne jointly with Cochlear Pty Ltd. The studies demonstrated substantial speech perception improvements over the current Multipeak strategy in background noise.
-
ItemElectrode position, repetition rate, and speech perception by early-and-late-deafened cochlear implant patients( 1993)Psychophysical and speech perception studies were conducted on eight patients using the 22electrode cochlear implant manufactured by Cochlear Pty. Ltd. Four early-deafened patients became deafened at 1-3 years of age and were implanted at 5-14 years of age. Four late-deafened (postlingual adult) patients became deafened at 38-47 years of age and were implanted at 42-68 years of age. Psychophysical studies measured the discrimination of trajectories with time-varying electrode positions and repetition rates. Speech perception studies measured performance using two speech coding strategies: a multi-electrode strategy which coded the first and second formant frequencies, the amplitudes of the two formants, and the fundamental frequency; and a single-electrode strategy which coded the amplitudes of the first and second formants, and the fundamental frequency. In general, the four late-deafened patients and one early-deafened patient were more successful than the other three early-deafened patients in the discrimination of electrode position trajectories and in speech perception using the multi-electrode strategy. Three of the four late-deafened patients were more successful than the early-deafened patients in the discrimination of repetition rate trajectories. Speech perception performance in the single-electrode strategy was closely related to performance in repetition rate discrimination. The improvement in speech perception performance from the single-electrode to multi-electrode strategy was consistent with successful performance in electrode discrimination.
-
ItemMultichannel cochlear implantation in children: a summary of current work at The University of Melbourne( 1991)This paper summarizes research work relating to multichannel cochlear implantation in children at the University of Melbourne. Ongoing safety studies relating to the implantation of young children are discussed. Results of these studies suggest that special design considerations are necessary for a prosthesis to be implanted in children under the age of 2 years. Results of clinical assessment of implanted children and adolescents are also discussed in terms of speech perception, speech production, and language development, and some possible predictive factors are suggested. Preliminary data suggests that a high proportion of young children can achieve open-set speech perception with the cochlear implant given appropriate training and support. Initial results with adults using new speech processing hardware and a new coding scheme are also presented. These suggest that improved speech perception in quiet and competing noise is possible with the new system.
-
ItemResults for two children using a multiple-electrode intracochlear implant( 1989)Abstract not available due to copyright.
-
ItemSpeech perception with cochlear implants and tactile aids [Abstract]( 1988)Abstract not available due to copyright.
-
ItemFactors affecting speech perception outcomes for older children using multichannel cochlear implants( 2002)Experience with cochlear implantation in early-deafened teenagers or young adults has been somewhat disappointing, however, in recent years a proportion of older children have demonstrated excellent speech perception performance. There appears to be a wide gap between the good and poor performers within this group. It is important to investigate the possible factors influencing performance so that adolescents and their families are able to make informed decisions regarding cochlear implant surgery. This study considered a number of factors in a group of 25 children implanted in Melbourne between the ages of 8 and 18 years. Each subject completed open set speech perception testing using BKB sentences before and after implantation and pre-operative language testing using the Peabody Picture Vocabulary Test. Data were collected regarding the type of hearing loss, age at implant, age at hearing aid fitting, audiometric details, and the pre-and postoperative communication mode. Multivariate analysis suggested that three factors have a significant predictive value for post-implant speech perception: pre-operative open-set sentence score, duration of profound hearing loss and equivalent language age. These three factors accounted for 66% of the variance in this group. The results of this study suggest that children who have useful pre-implant speech perception, and higher age-equivalent scores on language measures, would be expected to do well with a cochlear implant. A shorter duration of profound hearing loss is also advantageous. Mean speech perception scores for the older group were not significantly different from younger children.