Graeme Clark Collection

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1991 - 1994 6
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Author: McDermott, Hugh × Author: Vandali, Andrew × End date: 1999 × Start date: 1990 × Subject: cochlear implant ×

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Now showing 1 - 6 of 6
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    The spectral maxima sound processor: recent findings in speech perception and psychophysics
    McKay, Colette M. ; McDermott, Hugh J. ; Vandali, Andrew E. ; Clark, Graeme M. (Wien, 1994)
    The Spectral Maxima Sound Processor (SMSP) was developed at the University of Melbourne for use with the Mini System 22 implant manufactured by Cochlear Pty Ltd. The SMSP has been shown in recent studies to provide improved speech perception to implantees when compared to the currently commercially available processor for this implant (the MSP (MULTIPEAK) processor). In the first of three experiments, the effect on speech perception of increasing the rate of stimulation of the SMSP and of increasing the number of electrodes activated in each stimulation cycle was studied. It was found that these parameter changes made little difference to speech perception in quiet but both changes were advantageous for some subjects when listening in noise. The second and third experiments investigated psychophysically the effects of two aspects of the SMSP strategy which differ from previous processors for this implant. In the second experiment, it was found that concurrent stimulation of two adjacent or nearby electrodes evoked a pitch which was intermediate to that of either electrode. This may explain, in part, the better discrimination of vowel formants by users of the SMSP. In the third experiment, it was found that a pitch related to the modulation frequency was evoked by amplitude-modulating a constant rate stimulus, provided that the rate of stimulation was sufficiently high (four times the modulation frequency) or a multiple of the modulation frequency. This result may explain the equal ability of SMSP and MSP users to perceive speaker differences and intonation patterns, even though the rate of stimulation is constant In the SMSP.
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    A portable programmable digital sound processor for cochlear implant research
    McDermott, Hugh J. ; Vandali, Andrew E. ; van Hoesel, Richard J. M. ; McKay, Colette M ; HARRISON, MARK ; Cohen, Lawrence T. ( 1993)
    A programmable sound processor which utilizes digital signal processing has been developed for hearing prosthesis research. It incorporates a Motorola DSP56001 integrated circuit, 32K words of memory, a 12 b analog-to-digital converter, and a data formatter and transmitter which conveys control codes to the receiver-stimulator of a cochlear implant. The processor is pocket-sized and battery powered. It has been programmed to emulate the Spectral Maxima Sound Processor for the University of Melbourne/Nucleus 22 electrode implant, and is currently being used by several implantees. In continuing research, speech processing programs are being improved, and other applications, including signal processing for binaural implants and advanced hearing aids, are being developed.
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    A new portable sound processor for the University of Melbourne/ Nucleus Limited multielectrode cochlear implant
    McDermott, Hugh J. ; McKay, Colette M. ; Vandali, Andrew E. ( 1992)
    Abstract not available due to copyright.
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    Preliminary results with a six spectral maxima speech processor for The University of Melbourne/Nucleus multiple electrode cochlear implant
    McKay, Colette M. ; McDermott, Hugh J. ; VANDALI, ANDREW ; Clark, Graeme M. ( 1991)
    An improved sound processor for a multiple-channel cochlear implant hearing prosthesis has been developed. The spectral maxima sound processor (SMSP) extracts the six largest frequency components of speech and presents stimuli at a rate of 250 Hz to electrodes at positions selected on the basis of the spectral frequencies. It was designed for use initially with the advanced cochlear implant recently developed at the University of Melbourne, which is capable of high rate and quasi-simultaneous stimulation. The present study, however, was carried out with two subjects who have the more widely used 22-electrode implant produced commercially by Cochlear Pty Limited (formerly Nucleus Limited). Preliminary results comparing the performance of the SMSP with that of previous speech processing techniques (F0/F1/F2 strategy) are presented. The results indicate that the SMSP is capable of providing implanters with significantly greater information about speech.
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    An improved speech processor for a 22-electrode cochelar implant [Abstract]
    Clark, Graeme M. ; McKay, C. ; McDermott, H. ; Vandali, A. ( 1992)
    A spectral maxima speech processing strategy ( SMSP) has been developed as a result of research to improve the speech perception performance of a multiple-channel cochlear implant. With this speech processing strategy. the six spectral maxima from the outputs of 16 band pass filters are used to stimulate the cochlea on a place basis at a constant rate. This SMSP strategy has been compared with the MSP-MULTIPEAK strategy, the present speech processor provided by Cochlear Pty. Limited, on four postlinguistically deaf adults. The study showed that the SMSP strategy was significantly better than the MSP-MULTJPEAK for the recognition of closed-set vowels and consonants, and open-set monosyllable words and sentences in background noise.