Graeme Clark Collection

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    Speech cues for cochlear implantees: spectral discrimination
    Henry, Belinda, A. ; McKay, Colette M. ; McDermott, Hugh, J. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    The relationship between the ability of cochlear implantees to perceive speech and their ability to discriminate between stimulation on adjacent electrodes was investigated. Speech perception ability was assessed with monosyllabic words in 8 users Nucleus cochlear prosthesis. The ability of these subjects to discriminate between stimulation on adjacent electrodes, in of random loudness differences between electrodes was determined. Results were averaged in the apical, mid and basal regions of the cochlea. Regression analysis showed that speech perception ability and electrode discrimination ability were correlated in the apical to mid region of the cochlea. but the two factors were not correlated in the basal region. Therefore, these results suggest that implantees require the ability to discriminate between stimulation on adjacent electrodes in the apical to mid region of the cochlea in order to achieve high speech perception scores.
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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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