Graeme Clark Collection
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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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ItemSpeech recognition in adults with a severe hearing impairment [Abstract]( 1998)Adults with a severe hearing impairment comprise between 11.0% and 13.5% of the hearing-impaired population. From the perspective of audiological rehabilitation, understanding their difficulties offers many challenges. To investigate this population, a detailed investigation of the speech recognition of adults with severe hearing loss (N = 34) was conducted at The University of Melbourne. For the purposes of this study severe hearing impairment was defined as an average loss in the better ear of between 61 and 100 dB HL. Each participant took part in a series of speech recognition tasks while wearing their currently fitted hearing aids. The assessments included closed-set tests of consonant recognition and vowel recognition, combined with open-set tests of consonant recognition and vowel recognition, combined with open-set tests of monosyllabic word recognition, sentence recognition and the Connected Speech Test version 2 (CSTv2). Tests at the sentence level were also conducted in background noise (four-talkers superimposed) to replicate environments more typical of everyday listening conditions. Investigation of the results indicated a wide variability in performance between the participants on each of the speech perception measures. There were, however, some general trends which could be observed. As expected vowels were generally well perceived compared with consonants. Monosyllabic word recognition scores for the participants could be predicted from the segmental tests with an allowance for lexical effects. Scores for sentences presented in quiet showed additional linguistic effects and a significant decrease (p < .05) in performance with the addition of background noise. Additionally, the CSTv2 provided further insights into speech perception processes through the addition of further facilitative context. Discussion will also take place regarding the processes involved in speech perception and whether this population, despite severe auditory handicap are able to utilise restricted auditory input for higher level lexical processes.