Graeme Clark Collection

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Author: Clark, Graeme × End date: 1989 × Start date: 1980 × Subject: speech processing ×

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    A multiple-channel cochlear implant: an evaluation using open-set CID sentences
    Clark, Graeme M. ; Tong, Yit Chow ; Martin, Lois F. A. ( 1981)
    A multiple-channel cochlear implant and speech processor have been used in two postlingually deaf adult patients with a total hearing loss, to enable them to perceive varying degrees of running speech. The results have been confirmed with open-set CID everyday sentence tests. Using the implant alone, the patients obtained 8% and 14% scores with pre-recorded material, and 34% and 36% scores for "live" presentations. This was equivalent to the perception of 35% of connected discourse. When the implant was used in conjunction with lipreading, improvements of 188% and 386% were obtained over lipreading alone, and the scores were 68% and 98% which were equivalent to the perception of 60% and 95% of connected discourse.
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    Speech processing for a multiple-channel cochlear implant
    Tong, Y. C. ; Millar, J. B. ; Clark, Graeme M. ; Martin, L. F. ; Busby, P. A. ( 1980)
    A laboratory speech processor has been developed for a multiple-channel cochlear implant prosthesis. The speech processor accepts the speech waveform as an input and produces a pattern of electrical stimulus data as output. The electrical stimulus data are transmitted to the implanted receiver-stimulator by a transmitter which is external to the speech processor. Four speech signal parameters were estimated every 20 ms in the parameter estimation section of the speech processor. These parameters included the fundamental frequency (FO), a low frequency energy measure (AO) , the second formant frequency (F2) and its amplitude (A2).
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    Speech processing for a multiple-electrode cochlear implant hearing prosthesis
    Tong, Y. C. ; Clark, Graeme M. ; Seligman, P. M. ; Patrick, J. F. ( 1980)
    Abstract not available due to copyright.
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    Speech processing for a totally deaf patient with a multiple-electrode cochlear implant [Abstract]
    Clark, Graeme M. ; Tong, Y. C. ; Millar, J. B. ; Martin, L. F. ; Busby, P. A. ( 1980)
    A patient with a total hearing loss had a multiple-electrode cochlear implant performed on 1 August 1978 (Clark et. Al. 1979). Preliminary findings (Tong et al 1979) have shown that low and high pitch are discriminated on a place basis. Stimulating different electrodes produced the vowel colours.......
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    Temporal coding of speech information for cochlear implant patients
    Millar, J. B. ; Martin, L. F. A. ; Tong, Y. C. ; Clark, Graeme M. ( 1987)
    A modified speech-processing strategy incorporating the temporal coding of information strongly correlated with the first formant of speech was evaluated in a long-term clinical experiment with a single patient. The aim was to assess whether the patient could learn to extract information from the time domain in addition to the time domain cues for voice excitation frequency already received from the initial strategy. It was found that the patient gained no significant advantage from the modified strategy, but there was no disadvantage either, and the patient expressed a preference for the modified strategy for everyday use.
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    Evaluation of a two-formant speech-processing strategy for a multichannel cochlear prosthesis
    Dowell, R. C. ; Seligman, P. M. ; Blamey, P. J. ; Clark, Graeme M. ( 1987)
    Initial results with the two-formant speech-processing strategy (F0FIF2) confirm the advantage of a multichannel cochlear prosthesis capable of stimulating at different sites within the cochlea. The successful presentation of two spectral components by varying the place of stimulation leads to the possibility of presenting further spectral information in this manner. Because virtually all multichannel implant patients demonstrate good "place" (electrode site) discrimination, these more refined coding strategies should lead to benefits for the majority of implantees. Already, with the F0FIF2 strategy, we have a system that appears to provide some effective auditory-alone communication ability for the average patient.
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    Speech processing for cochlear implant prostheses
    Millar, J. B. ; Tong, Y. C. ; Clark, Graeme M. ( 1984)
    The transformation of speech into electrical signals which can stimulate the auditory nerve in order to create hearing sensations that carry speech information depends on many factors. These include the limitations imposed by the current state-of-the-art in otological surgery, microelectronic and micromechanical technology, and knowledge of the functioning of the auditory system under both acoustic and electrical stimulation. Sufficient advances have been made in all these areas to enable several research centers to develop cochlear prostheses which give some hearing to certain totally deaf persons. The work of these centers towards the goal of full unaided speech perception via the prosthesis is examined and evaluated.
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    A speech processing strategy for multiple-electrode cochlear implant prostheses
    Tong, Y. C. ; Clark, Graeme M. (Monash University Press, 1983)
    Speech studies in a number of research centres have shown that useful speech information could be presented to deaf patients using single or multiple electrode cochlear implant prostheses (Parking & Anderson, 1983). In our laboratory, speech processing strategies were formulated on the basis of psychophysical results. This paper examines the psychophysical characteristics of the hearing sensations produced by electrical stimulation using scala tympani electrodes in postlingually deaf patients; a speech processing strategy is then discussed on the basis of these characteristics.
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    Percepts from scala tympani stimulation
    Tong, Y. C. ; Clark, Graeme M. ( 1983)
    This report summarizes the characteristics of the hearing sensations produced by electrical stimulation using scala tympani electrodes in a postlingually deaf patient (MC1) at the University of Melbourne. An array of 10 electrodes, spaced 1.5 mm apart, was inserted through the round window for a distance of 15 mm around the scala tympani. Biphasic current pulses with each phase fixed at 180 /μsec were used. Fifteen current levels from 67 /μA to 1 rnA could be assigned in 67-/μA steps, and a maximum repetition rate of 1000 rep/sec was possible. More detailed descriptions of the stimulation hardware and the patient's history can be found in previous reports.
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    Selection of speech processing for cochlear implant prostheses
    Millar, J. B. ; Tong, Y. C. ; Clark, Graeme M. (Monash University Press, 1983)
    In this paper we consider a framework against which to discuss strategies for the design of speech processors for cochlear implant prostheses. We hope to encourage discussion of the bases for such a framework even though it may seem a distant objective owing to the large gaps in our understanding of several component parts of cochlear implant systems. The existence of such a framework would provide a background against which to view the current diverse cochlear implant systems and to evaluate their performance.