Graeme Clark Collection

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1976 - 1977 3
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Author: Patrick, James × End date: 1977 ×

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    A multiple electrode cochlear implant
    Clark, Graeme M. ; Tong, Y. C. ; Black, R. ; Forster, I. C. ; Patrick, J. F. ; Dewhurst, D. J. (Cambridge University Press, 1977)
    It is generally agreed that if a cochlear implant hearing prosthesis is to enable a patient to understand speech, it must be a multiple-electrode system. In addition, stimulation of the auditory nervous system should approximate the patterns of neural excitation occurring in people with normal hearing, and this is especially important when a patient has previously experienced hearing. For this reason the correct application of electrophysiological principles to the design of a hearing prosthesis is desirable, and is discussed in this paper with special reference to a device developed in the Departments of Otolaryngology and Electrical Engineering at the University of Melbourne (UMDOLEE).
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    A multiple-electrode hearing prosthesis for cochlear implantation in deaf patients
    Clark, Graeme M. ; Black, R. ; Dewhurst, D. J. ; Forster, I. C. ; Patrick, J. F. ; Tong, Y. C. ( 1977)
    A multiple-electrode hearing prosthesis for cochlear implantation in deaf patients has been developed at the University of Melbourne. It has been designed as a multiple-electrode implant to provide the best chance of enabling patients to understand speech. It has been shown that an electrode array can be threaded along the coils of the inner ear close to residual auditory nerves. Experimental studies have indicated that the long-term implantation of the array will not lead to significant degeneration of auditory nerve fibres. Loss of platinum from the stimulating electrodes can be minimized with a biphasic constant current pulse, where the first phase is negative with respect to ground. The receiver-stimulator component has also been designed to provide 10 - 15 channels of stimulation. Furthermore, the phase and amplitude of the stimuli to individual electrodes can be varied to enable the localization of the electrical fields to discrete groups of nerve fibres, and the correct method of frequency and intensity coding to be determined. Finally, the device should be used in the first instance for a specially selected group of adults who are post-lingually deaf.
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    Speech analysis and synthesis [Abstract]
    Tong, Y. C. ; Clark, Graeme M. ; Patrick, J. F. ; Gwyther, J. L. ( 1976)
    Speech sounds are digitized and stored in mass storage units of a Hewlett Packard computer system. A short-time frequency analysis of the speech sounds is then performed, and sound spectrographs are displayed on a Tektronix 4014 terminal. The speech sounds are also processed using a digital computer model of hasilar membrane motion, and envelope details of the cochlear analysis are displayed using the same technique as the sound spectrograph. Speech sounds are synthesized by rule using a hardward terminal analog synthesizer. A digital computer is used to translate a sequence of phonemes which comprise the speech sound into the control signals required by the synthesizer.