Graeme Clark Collection
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ItemImproved sound processing for cochlear implants( 2002)Four signal processing schemes currently under development aim to improve the perception of sounds/ especially speech, for children and adults using the Nucleus cochlear implant system. The schemes are (1) fast-acting input-signal compression, (2) Adaptive Dynamic Range Optimisation (ADRO), (3) TESM, a scheme that emphasises transients in signals, and (4) DRSP, a strategy that applies different stimulation rates to selected sets of electrodes.
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ItemWhat factors contribute to successful outcomes for children using cochlear implants( 2000)Long term speech perception data has been collected for 100 children using the Nucleus multichannel cochlear prosthesis in Melbourne. Scores on a number of different assessments are available at approximately six month intervals following implantation for these children. The group represents an unselected sample of cochlear implant users, as all children were included if they had sufficient developmental skills to perform formal speech perception tests. Information was also collected on each child regarding type of hearing loss, age of onset of profound hearing loss, duration of profound hearing loss, age at implantation, pre and post-implant communication mode, developmental delay, speech processing strategy and length of experience with implant use.
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ItemLatest results for adults & children using cochlear implants & future implications( 2000)The overall success of a cochlear implant procedure is most often quantified by assessing how well implantees can understand speech. This is because a primary aim of the application of cochlear implants is to improve communication, and it is relatively straightforward to obtain accurate measures of speech recognition. The quality of cochlear implant hearing is not well described by measuring an audiogram, as the detection of sound is similar across all implantees if the device is functioning correctly. A commonly used measure of speech understanding is the CID everyday sentence test where the number of correctly identified words within sentences is assessed. In the early days of cochlear implants, subjects could only recognize a few words without lipreading but the most recent results show average scores of 80% without lipreading for this sentence test, after 6 months of experience with the device.
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ItemThe effect of language knowledge on speech perception: what are we really assessing? [Abstract]( 1996)It is a common finding that many hearing-impaired children have poorer language skills than their normally-hearing peers of the same age. It is also logical to assume that the measurement of open-set speech perception in children with cochlear implants could be affected by limited receptive vocabulary and syntactic knowledge. Therefore, we may be significantly underestimating the speech perception abilities of some hearing-impaired children.
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ItemComparative performance of children using the cochlear 22-channel implant and 8-channel 'Tickle Talker'( 1992)Direct comparison of "Tickle Talker" and Cochlear Implant users is problematic, due to difficulties in matching groups of children for hearing loss, age, duration of deafness, speech perception and language skills, and educational placement. However, two studies were undertaken to compare and contrast potential benefits available from these two devices. In the first study, a number of children from one educational setting were evaluated over a six month period. Half of the children used the multiple channel cochlear implant, while the other half used the multiple channel "Tickle Talker". The number of training sessions, clinicians involved, type of training provided, and overall management philosophy were identical for both devices. Comparison of progress of these two groups of children demonstrates that both devices are effective in improving' communication. However, differences were found with the tactile device being more limited in information provided and speech perception benefits. In the second study, two children who have used both devices were evaluated. These two children initially used the ''Tickle Talker" for periods up to two years, and subsequently had a multiple-channel cochlear implant. Similar habilitation was provided to these children with both devices, and measures of speech perception were taken at similar time periods. Results for one of the children, a prelinguistically deafened adolescent, already show similar benefits in terms of supplementation of lipreading for both devices. However, this patient has also shown some open-set word and sentence perception using the implant-alone. To date, this level of performance has not been achieved with the ''Tickle Talker". The results of these studies suggest a role for a multiple channel tactile device in a cochlear implant clinic as a training device for evaluating the ability of adults or children to integrate speech information presented through different sensory modalities. This could facilitate pre-implant evaluation of the potential for children to benefit from added speech information, which is often difficult to evaluate in congenitally deaf children.
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ItemDevelopment of an advanced electrotactile speech processor [Abstract]( 1992)Initial studies with a multiple channel electrotactile speech processor ('Tickle Talker') showed that profoundly hearing-impaired adults and children could achieve significant improvements on speech perception tests through use of tactual-encoded estimates of fundamental frequency, second formant frequency and amplitude envelope. Results showed that the device provided tactual cues which could be used to discriminate speech features such as vowel length and place, and consonant manner and voicing. However, discrimination of initial consonant voicing was not as consistent as for other features. Accurate discrimination of consonant voicing and manner (particularly high frequency information) is critical, since this Information is generally inaudible through hearing aids, and difficult to lipread.