Graeme Clark Collection
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ItemThe University of Melbourne/Nucleus cochlear prosthesis( 1988)This is a review of research to develop the University of Melbourne/Nucleus cochlear prosthesis for patients with a profound-total hearing loss. A more complete review can be obtained in Clark et al. A prototype receiver-stimulator and multiple-electrode array developed at the University of Melbourne was first implanted in a postlingually deaf adult patient with a profound-total hearing loss on 1 August 1978. A speech processing strategy which could help this patient understand running speech, especially when combined with lipreading was developed in 1978 following initial psychophysical studies. A prototype wearable speech processor was fabricated in 1979, that could provide significant help for the first two patients in understanding running speech when used in combination with lipreading compared with lipreading alone, and it also enabled them to understand some running speech when using electrical stimulation alone. An implantable receiver-stimulator and wearable speech processor embodying the principles of the prototype devices were then produced for clinical trial by the Australian biomedical firm, Nucleus Ltd, and its subsidiaries, Cochlear Pty Ltd and Cochlear Corporation. This cochlear implant was initially clinically trialled on six patients at The Royal Victorian Eye & Ear Hospital in 1982, and shown to give similar results to those obtained with the prototype device. In view of these findings a clinical trial was carried out for a Premarket Approval Application to the US Food and Drug Administration (FDA), and extended to a number of centres in the US, Canada, and West Germany. This clinical trial confirmed that patients could understand running speech when electrical stimulation was combined with lipreading, and that some patients could also understand running speech when using electrical stimulation alone. Today, more than 600 patients world-wide are using cochlear implants developed from the research described in this paper.
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ItemA multi-channel hearing prosthesis for profound-to-total hearing loss( 1984)A multi-channel cochlear implant hearing prosthesis providing 22 separate channels of stimulation has been developed. The electronics for the implantable receiver-stimulator have been incorporated on a single chip, using digital circuits and employing CMOS technology. The chip is enclosed in a titanium capsule with platinum/ceramic electrode feed-throughs. A pocket-sized speech processor and directional microphone extract the following speech parameters: signal amplitude, fundamental frequency and formant frequency. The fundamental frequency is coded as electric pulse rate, and formant frequency by electrode position. The speech processor has been realized using hybrid circuits and CMOS gate arrays. The multi-channel prosthesis has undergone a clinical trial on four postlingually deaf patients with profound-total hearing losses. The speech perception results indicate that they were able to obtain open-set speech recognition scores for phonetically balanced words, CID sentences and spondees. In all cases the tests showed significant improvements when using the cochlear prosthesis combined with lipreading compared to lipreading alone.
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ItemA multi-channel cochlear prosthesis for profound-to-total hearing loss( 1984)A multi-channel cochlear prosthesis for profound-total hearing loss has been developed by the University of Melbourne and Nucleus Limited. Clinical trials have shown that the prosthesis provides significant help for postlingually deaf adult patients (lost hearing after normal language patterns have been established). The prosthesis helps the patients understand running speech when combined with lipreading, and a proportion obtain significant open-set speech scores for electrical stimulation alone. The patients with these open-set score can use the device in situations where lipreading is not possible, for example, to converse over the telephone. The prosthesis consists of an externally worn, pocket-sized speech-processor, a headset and an implanted receiver/stimulator and electrode array. The headset contains an .ear-level directional microphone that picks up the speech signal. The speech processor encodes the speech as a series of electrical pulses on the electrode array. The data describing these pulses and the power required to produce them, are sent to the receiver/stimulator from .a radio-frequency coil mounted on the headset. The receiver/stimulator decodes the data and delivers the speech signal as a series of biphasic electrical pulses to the 22 electrodes which have been gently passed along the scala tympani during implantation.
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ItemClinical trial of a multi-channel cochlear prosthesis: results on 10 postlingually deaf patients( 1984)The clinical trial of a multi-channel cochlear prosthesis has been carried out on 10 profoundly-totally deaf adult patients. Speech perception tests have shown that all the patients received significant benefit from the device. They obtained improvements in understanding running speech from 47% to 550% when using the device in conjunction with lipreading compared to lipreading alone. With an open-set CID sentence test, three patients obtained scores showing an ability to understand speech without the need to lipread, and a further three patients had scores indicating they could also receive useful information without lipreading. In two patients, very limited open-set scores for electrical stimulation alone were obtained. This was most probably due to the fact that only a few channels of stimulation were possible due to cochlear disease and they were therefore receiving information more like a single-channel device. The prosthesis has also been found to provide considerable help in hearing and recognizing everyday sounds.