Graeme Clark Collection
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ItemA multiple-channel cochlear implant: evaluation using speech tracking( 1981)Two totally deaf patients who had received multiple-channel cochlear implants were tested using a speech "tracking" procedure in which they had to repeat verbatim passages of connected discourse. Their performance was assessed by calculating the tracking rate (words per minute) each session. Testing was carried out under two conditions - lipreading along and lipreading in conjunction with a multiple-channel cochlear implant and laboratory speech processor. Lipreading with the cochlear implant increased the tracking rates by a factor of four for one patient and by a factor of two for the other when compared with lipreading alone.
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ItemA multiple-channel cochlear implant: an evaluation using nonsense syllables( 1981)A study using nonsense syllables has shown that a multiple-channel cochlear implant with speech processor is effective in providing information about, voicing and manner and to a lesser extent place distinctions. These distinctions supplement lipreading cues. Furthermore, the average percentage improvements in overall identification scores for multiple-channel electrical stimulation and lipreading compared to lipreading alone were 71% for a laboratory-based speech processor and 122 % for a wearable unit.
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ItemA multiple-channel cochlear implant: an evaluation using an open-set word test( 1981)Multiple-channel electrical stimulation of the hearing nerve in conjunction with speech reading has helped two post-lingually deaf patients with total hearing losses understand running speech in every day situations. This has been confirmed using open-set phonetically balanced word tests, where the patients achieved 60% and 40% scores with isolated-words and 80% and 73% for phonemes-in-isolated words. The tests also showed that the cochlear implant improved word recognition by a factor of four in one patient and two in another compared with speechreading alone. The speech processor used extracted the voicing frequency and energy and the frequency and energy of the dominant spectral peak in the mid-frequency range. The parameters for voicing determined the rate of stimulation for all electrodes, and the parameters for the dominant spectral peak in the midfrequency range determined the site of electrode stimulation and current level.
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ItemSpeech processing for a multiple-channel cochlear implant( 1980)A laboratory speech processor has been developed for a multiple-channel cochlear implant prosthesis. The speech processor accepts the speech waveform as an input and produces a pattern of electrical stimulus data as output. The electrical stimulus data are transmitted to the implanted receiver-stimulator by a transmitter which is external to the speech processor. Four speech signal parameters were estimated every 20 ms in the parameter estimation section of the speech processor. These parameters included the fundamental frequency (FO), a low frequency energy measure (AO) , the second formant frequency (F2) and its amplitude (A2).
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ItemSpeech processor design for a multiple-channel cochlear implant( 1980)This paper outlines the strategy adopted for a laboratory-based speech processor used to provide speech information to patients with a multiple-channel cochlear implant It also presents the results of vowel and consonant recognition studies and speech test using open sets of words and sentences.
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ItemThe rehabilitation of patients with a total hearing loss using a multiple-channel cochlear implant [Abstract]( 1980)Two profoundly deaf patients who have multiple-channel cochlear implants receive speech information through a speech processor. The speech processor encodes second formant and fundamental frequency information. Rehabilitation is concerned with evaluating the speech processor and training patients to improve speech perception. The patients have scores up to 37% and 27% on AB word lists, and 36% and 34% on NAL Everyday Sentences using the cochlear implant alone and repetition of the stimuli. However, to gain a better insight into the capabilities of the speech processor and to demonstrate its potential for the patients more investigative procedures have been used. These include the speech tracking method described by DeFillipo and Scott (1978) using the cochlear implant in conjunction with speech reading. Results indicate that patients have gained a two-fold and four-fold improvement in tracking rates (words per minute) using speech reading and the cochlear implant as opposed to speech reading alone.
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ItemPhonemic information transmitted by a multichannel electrotactile speech processor( 1988)A wearable electrotactile speech processor was evaluated in a study with seven normally hearing and four hearing-impaired subjects. The processor estimated the fundamental frequency, the second-formant frequency, and amplitude of the acoustic speech signal. These parameters were presented as a pattern of electrical pulses applied to eight electrodes positioned over the digital nerve bundles on one hand. The device was shown to provide useful information for the recognition of phonemes in closed sets of words using tactile information alone. The device also supplemented lipreading to improve the recognition of open-set words. The recognition of duration and first-and second-formant frequencies of vowels and the recognition of voicing and manner of consonants were improved over recognition with lipreading alone. Recognition of final consonants was improved more than recognition of initial consonants. These results indicate that the device may be useful to both severely and profoundly hearing-impaired people.
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ItemEvaluation of training strategies with an electrotactile speech processor [Abstract]( 1988)During 1986, seven normally-hearing subjects were trained in the use of an electrotactile speech processor ("Tickle Talker"). Two training methods were used: (a) a combined strategy. in which a variety of training materials ranging from analytic to synthetic level were employed; and (b) a synthetic alone training strategy, in which only synthetic level training materials were used. All seven subjects received 70 hours of training, 35 hours in each training strategy. Subjects were evaluated in the tactile-lipreading (TL) and lipreading alone (L) conditions at: (I) 0 hours training; (2) 35 hours training; and (3) after 70 hours of training. An evaluation test battery was constructed which contained both closed-set and open-set materials. Results indicated differences in performance on the evaluation tests which were dependent upon the training strategy. The differences in performance were greater in some evaluation tests than others. Subsequently; seven severe-profoundly hearing-impaired children (aged 7-11) have been fitted with the Tickle Talker and are presently participating in an ongoing training programme. Evaluation of their performance will help to assess the suitability of the device for young children.
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ItemInterim results of open-set speech discrimination with a wearable multichannel electrotactile speech processor( 1987)Abstract not available due to copyright.
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ItemAcoustic parameters measured by a formant-estimating speech processor for a multiple-channel cochlear implant( 1987)Abstract not available due to copyright.