Graeme Clark Collection

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    Speech processing for cochlear implants: variations of the spectral maxima sound processor
    McKay, Colette M. ; Vandali, Andrew E. ; McDermott, Hugh J. ; Clark, Graeme M. ( 1993)
    The Spectral Maxima Sound Processor (SMSP) incorporates a bank of sixteen band-pass filters which are assigned to sixteen intracochlear electrodes. In each stimulation period six electrodes are activated, based on the outputs of the filters with the largest amplitudes. The SMSP has been compared with the present MSP(MULTIPEAK) processor and found to improve speech comprehension results. The SMSP speech processing scheme has recently been implemented successfully in a new speech processor, also developed at the University of Melbourne, which utilises digital signal processing techniques. The programming flexibility of the new processor has facilitated the investigation of variations of the SMSP strategy which might provide further enhancement of speech perception. Three variations have been investigated: firstly, increasing the constant pulse rate from the usual 250Hz to 400Hz; secondly, changing the number of electrodes selected in each stimulation period from six to numbers between four and eight; thirdly, sharpening the spectral peaks prior to selection of the active electrodes. The results of these studies showed that all three variations had minimal effect on speech perception in quiet, but that increasing the number of electrodes selected for stimulation to eight, or increasing the rate of stimulation, may have advantages when listening in background noise.
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