Graeme Clark Collection

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Start date: 2000 × End date: 2009 × Subject: otolaryngology × Subject: cochlear implants × Subject: speech processing ×

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    Inner ear implants
    Clark, Graeme M. (Dekker, 2004)
    The cochlear implant is an electronic device that brings useful hearing to severely to profoundly deaf people through multiple-channel electrical stimulation of the auditory nerves in the inner ear. This is required if their inner ears are so badly damaged by injury and disease, or so inadequately developed, that they cannot provide sufficient hearing for communication, even when the sound is amplified with a hearing aid. By stimulating the nerve directly with patterns of electrical pulses, the implant bypasses the normal function of the sense organ of hearing in the inner ear to partially reproduce the coding of sound. It consists of a wearable speech processor that picks up sound with a microphone, analyzes the signal, and then sends it by radio waves to the implanted receiver stimulator, which decodes the message and stimulates the electrode wires inserted into the inner ear.
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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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    Chronic monopolar high rate simulation of the auditory nerve: physiological and histopathological effects
    TYKOCINSKI, MICHAEL ; Linahan, Neil ; Shepherd, R. K. ; Clark, Graeme M. (Kugler Publications, 2001)
    There is clinical interest in the development of high rate speech processing strategies, since there are indications that these might enhance speech perception due to an improved representation of the rapid variations in amplitude of speech. Significant improvement in speech perception using high rate stimulation has been demonstrated in cochlear implant recipients. However, it is important that the long-term safety of high rate stimulation is clearly established prior to its general clinical application. This is especially important, since acute animal studies have shown that high rate stimulation can induce a reduction in the excitability of the auditory nerve. This was also associated with an increase in both threshold and latency of the electrically evoked auditory brainstem response (EABR). However, while a chronic stimulation study indicated that monopolar electrical stimulation of the auditory nerve at rates of 1000 pulses per second (pps)/channel (three channels) had no adverse effects on the spiral ganglion cell density (SGCO),5 there is limited data concerning higher rates. In the present study, we evaluated the electrophysiological and histopathological effects of chronic monopolar electrical stimulation of the auditory nerve using considerably higher stimulus rates than have been used in previous studies.