Graeme Clark Collection

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    A comparison of a new prototype Tickle Talker with a Tactaid 7
    Galvin, Karyn L. ; Ginis, Jan ; Cowan, Robert S. C. ; Blamey, Peter J. ; Clark, Graeme M. ( 2001)
    This study compared the speech perception enhancement provided by two multichannel tactile aids: a new version of the Tickle TalkerT™ and the Tactaid 7. The subjects' impression of benefit was also examined. In an AB pattern, six adults with hearing impairment used each device daily for approximately 18 weeks and attended 12 training sessions. When tactile information was provided, the group demonstrated a significant enhancement for the perception of words (mean 17.2%) and phonemes (mean 12.9%) in monosyllabic word lists, words in sentences (mean 14.2%) and speech tracking (mean 7.7 wpm). The Tactaid 7 provided a significantly greater enhancement for the perception of words (21 % versus 13.4%), phonemes (16.7% versus 9.1%) and some speech features in monosyllabic word lists. Subjective ratings were slightly higher for the Tactaid 7, and four subjects preferred this device. Either device may be suitable for those not able or willing to have a cochlear implant.
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    Improved sound processing for cochlear implants
    James, C.J. ; Just, Y. ; Knight, M.R. ; Martin, L.F.A. ; McKay, C.M. ; Plant, K.L. ; Tari, S. ; Vandali, A.E. ; Clark, Graeme M. ; Cowan, R.S.C. ; McDermott, H. J. ; Blamey, P. J. ; Dawson, P. ; Fearn, R. A. ; Grayden, D. B. ; Henshall, K. R. ( 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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    A comparative study of phase-contrast and conventional x-ray imaging in human temporal bone samples
    XU, JIN ; TYKOCINSKI, MICHAEL ; Saunders, E. ; Clark, Graeme M. ; Cowan, R. ( 2001)
    This study compared a new x-ray modality, phase-contrast radiography, with conventional radiography for imaging in human temporal bones and also investigated its potential application in the development of electrode arrays for advanced cochlear implants. Nucleus standard electrode arrays and peri-modiolar Contourn.4 electrode arrays were implanted into the cochleae of 10 human temporal bones. Both conventional and phase-contrast radiographs were taken of ~ach temporal bon~. The phase-contrast radiographs showed significant improvements over conventional radiographs in the detail of temporal bone images. These improvements included enhanced contrast at the edge of canal type features, inherent image magnification, higher spatial resolution, and ability to use detectors such as Imaging Plates. The results demonstrate that phase-contrast imaging can have important advantages in visualisation of anatomical details of both the inner ear structures and the microelectrode. It can provide a clearer definition of electrode location in relation to cochlear walls. This study demonstrates the feasibility of applying phase-contrast radiography to studies of the human temporal bone. However, its usefulness in the imaging of larger objects or perhaps even with patients in a clinical setting will require further investigation.
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    Application of advanced radiographic technology in cochlear implant research
    XU, JIN ; TYKOCINSKI, MICHAEL ; Saunders, E. ; Clark, Graeme M. ; Cowan, R. ( 2001)
    The effective development of peri-modiolar or other advanced electrode arrays for cochlear implants requires detailed analysis of the insertion procedure and electrode positioning in the cochlea. Routine x-ray techniques cannot provide sufficient detail to meet this need. A new micro-focus x-ray imaging system has been built for our research. The system consists of a x-ray tube with a sub 10-micron focal spot mounted below an adjustable work surface and an image intensifier placed approximately 100 cm above the x-ray aperture. A variety of intracochlear electrode arrays and human temporal bones were studied using this system. The micro-focus x-ray imaging system allows for micro-fluoroscopy to visualise the real time implantation procedure. It also enables capturing of images onto reusable phosphor imaging plates or films for subsequent viewing or analysis. Images are produced at up to 95 times magnification with superior resolution and enhanced contrast. This new radiographic technology plays an important role in development of safe and effective advanced intracochlear electrode arrays.
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    Safety studies and preliminary patient trails with a new perimodiolar electrode array
    Clark, Graeme M. ; COWAN, ROBERT ; Saunders, Elaine ; TYKOCINSKI, MICHAEL ; COHEN, LAWRENCE ; Treaba, Claudiu ; BRIGGS, ROBERT ; Dahm, Markus ( 2000)
    A new perimodiolar electrode array, the curly-with stylet (CwS), has been developed and undergone safety trials in human cadaver temporal bones. The array was developed as a result of animal and modelling studies which indicated that there are potential advantages in situating the electrode array in closer proximity to the neural elements. Preliminary studies with four patients in Melbourne implanted with a developmental pre-curved array had supported the predictions of lower current requirements and possibly more focussed spread of excitation.
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    What factors contribute to successful outcomes for children using cochlear implants
    Cowan, Robert C. ; Clark, Graeme M. ; Dowell, Richard C. ; Dettman, Shani J ; Barker, Elizabeth ; Latus, Katie ; Hollow, Rod ; Blamey, Peter J. ( 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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    Hearing levels and speech perception prior to cochlear implantation - are they predictive of outcomes for adult implant users?
    Dowell, Richard C. ; Winton, Elizabeth ; Ling, Caroline ; Hollow, Rod ; COWAN, ROBERT ; Clark, Graeme M. ( 2000)
    As the speech perception results obtained for adults using multichannel cochlear implants have improved, people with a wider range of hearing losses are now considering implantation. In the mid-1980s, most adults undergoing cochlear implantation had little or no residual hearing. This made selection and counselling relatively straightforward as any level of hearing obtained through use of the cochlear implant could be considered as a benefit in such cases. Most patients evaluated for implantation today have some degree of useful residual hearing, and may be reliant on this hearing to varying degrees in their everyday life. In essence, they have something to lose if their postoperative performance is poor. In counselling these patients, it would be most helpful to have reliable predictors of postoperative performance. A number of factors such as duration of profound hearing loss, congenital profound hearing loss, and certain aetiologies (eg, head injury) have shown significant links with outcomes in previous studies.
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    How much residual hearing is too much?
    Cowan, R. S. C. ; Dowell, R. C. ; Psarros, C. ; Dettman, S. J. ; Rance, G. ; Clark, Graeme M. ( 2000)
    The value of cochlear implants as an established clinical option for profoundly hearing-impaired adults and children has been supported by significant research results over a number of years (U.S. National Institutes of Health Consensus Statement 1995). As a direct consequence of the level of benefits shown for cochlear implant users on measures of speech perception, research has focused on investigating whether severely hearing impaired adults and children would be suitable candidates for cochlear implantation. I n considering the candidature of any individual, both medical and audiological suitability are investigated. The primary concern is to establish to what degree the patient would benefit from use of the cochlear implant.