Graeme Clark Collection

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Subject: cochlear implant × Subject: speech processor × Start date: 1992 × End date: 1992 ×

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Now showing 1 - 5 of 5
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    An extension of the Multipeak speech processing strategy for the MSP/MINI 22 cochlear implant system
    Jones, P. A. ; McDermott, H. J. ; Sellgman, P. M. ; Millar, J. B. ( 1992)
    The speech perception of three post-linguistically deaf adults using the Nucleus MSP/Mini System 22 cochlear implant system programmed with a new speech processing strategy, MPEAK+AO. was evaluated. The MPEAK+AO strategy retains all the information of the standard Multipeak speech processing strategy and additionally presents acoustic components below 400Hz to the most-apical electrode. This extra spectral Information may help implantees understand speech, particularly in noise. Since the estimated fundamental frequency is presented as the rate of stimulation at a fixed intracochlear site and is thereby potentially perceived more easily. and the amplitude of the stimulation on the apical electrode, associated with the voice fundamental, Is directly determined from the estimated energy in the relevant spectral region. these coding factors may provide a better representation ot the prosodic information in speech and a more complete auditory feedback signal. The comparison between Multipeak and MPEAK+AO included tests of vowel, consonant and CNC word recognition. Speech materials were presented with both a male and female speaker. Sentence material. presented with background masking noise (four-speaker babble) was also used. The results showed that the new strategy significantly improved the ability of these MSP users to recognise words in open-set sentences in noisy conditions.
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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.
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    A new algorithm for voicing detection and voice pitch estimation based on the neocognitron
    Moxham, James R. E. ; Jones, Peter A. ; McDermott, Hugh D. ; Clark, Graeme M. ( 1992)
    Over the last decade cochlear implants have been used increasingly to restore hearing to the profoundly deaf. One of the more widely used implants is the Nucleus multi-electrode implant, developed by the University of Melbourne and Cochlear Pty. Ltd. The speech processor used with this implant is the MSP, programmed with the multipeak strategy. This device incorporates circuits to estimate the fundamental frequency (FO) of speech signals, and to decide whether voicing is present. This paper describes a new FO estimator and voicing detection algorithm based on the neocognitron; a neural network modelled on the retina and early visual system. Performance was compared with that of three other FO estimation algorithms: linear predictive coding (LPC), cepstral analysis and the algorithm used in the Multipeak-MSP processor. For the speech samples tested, the neocognitron performed more reliably than the other three systems. On the basis of these results, this work may be able to provide benefits to existing and future cochlear implant users.
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    Development of an advanced electrotactile speech processor [Abstract]
    Cowan, Robert S. C. ; Blamey, Peter J. ; Glavin, K. L. ; Sarant, J. Z. ; Millard, R. ; Clark, Graeme M. ( 1992)
    Initial studies with a multiple channel electrotactile speech processor ('Tickle Talker') showed that profoundly hearing-impaired adults and children could achieve significant improvements on speech perception tests through use of tactual-encoded estimates of fundamental frequency, second formant frequency and amplitude envelope. Results showed that the device provided tactual cues which could be used to discriminate speech features such as vowel length and place, and consonant manner and voicing. However, discrimination of initial consonant voicing was not as consistent as for other features. Accurate discrimination of consonant voicing and manner (particularly high frequency information) is critical, since this Information is generally inaudible through hearing aids, and difficult to lipread.