Graeme Clark Collection
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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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ItemManikin and cochlear implant patient test results with a portable adaptive beamforming processor to suppress the effects of noise( 1995)A simple adaptive beamformer (ABF) was implemented in a real-time portable speech processor and tested with four cochlear implant patients. The ABF algorithm used signals from only two microphones - one behind each ear - to attenuate sounds not arriving from the direction directly in front of the patient, and was compared with a strategy in which the two microphone signals were simply added together (two-microphone broadside strategy). Tests with the four patients were conducted in quiet and in noise. Results at a 0 dB signal-to-noise ratio showed large improvements in speech intelligibility for all patients, when compared to the two-microphone broadside strategy. Physical measurement of the directional characteristics of the ABF processor were made with a Kemar manikin. The effects of reverberation were explored by placing the manikin in different acoustic environments and observing the attenuation of the noise alone at various angles. A near-anechoic environment allowed the noise to be attenuated by as much as 21 dB, whereas in a highly reverberant concrete stairwell, the ABF processor was unable to provide any directional gain beyond about 3 dB.
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ItemArchitecture of the Spectra 22 speech processor( 1995)The Spectra 22 is a logical extension in the development of the speech processing for the Cochlear Mini 22 system. It can implement the new coding strategy (Speak) that has provided significant improvement in patient benefit.
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ItemEvaluation of a portable two-microphone adaptive beamforming speech processor with cochlear implant patients( 1995)Abstract not available due to copyright.
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ItemCombined electrical and acoustical stimulation using a bimodal prosthesis( 1993)A new device incorporating a cochlear implant speech processor and a speech-processing hearing aid for the un-implanted ear has been designed and tested with four severely hearing-impaired patients. The aim of the device is to provide a more acceptable and effective combination of electrical and acoustic signals to the two ears. When used monaurally, and binaurally in conjunction with the cochlear implant, the speech-processing hearing aid mean scores for open-set sentences, words, and consonants were as good as or better than the mean scores for the patients' own conventional hearing aids. Some patients improved much more than did others. Although not conclusive, these results are encouraging, especially as they were achieved with a laboratory prototype that did not allow the patients to become accustomed to the processor in everyday situations.
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ItemThe development of the nucleus multiple-channel cochlear implant( 1993)Physiology, biology, psychophysics and speech research studies led to the development of the inaugural cue-extraction speech processing strategy used in the Nucleus multiple-channel cochlear implant. This resulted in postlinguistically deaf adults obtaining open-set word scores for electrical stimulation alone, as well as significant improvements in understanding running speech when electrical stimulation was combined with lip-reading. Further speech processing research has resulted in progressive improvements in speech perception for postlinguistically deaf adults. The improvements have principally involved presenting more spectral information on a place coding basis, but additional temporal information has also improved its performance. The cue-extraction or speech-feature strategies used with the multiple-channel implant have also been shown to provide postlinguistically and prelinguistically deaf children (two to 17 years of age) with significant help in communication. In the children, open-set speech scores are most frequently obtained in the youngest age groups, and with longer periods of auditory training.
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ItemSpeech processing for cochlear implant prostheses( 1984)The transformation of speech into electrical signals which can stimulate the auditory nerve in order to create hearing sensations that carry speech information depends on many factors. These include the limitations imposed by the current state-of-the-art in otological surgery, microelectronic and micromechanical technology, and knowledge of the functioning of the auditory system under both acoustic and electrical stimulation. Sufficient advances have been made in all these areas to enable several research centers to develop cochlear prostheses which give some hearing to certain totally deaf persons. The work of these centers towards the goal of full unaided speech perception via the prosthesis is examined and evaluated.
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ItemA 12-consonant confusion study on a multiple-channel cochlear implant patient( 1982)A consonant confusion study was undertaken on a multiple-channel cochlear implant patient using a wearable speech processing device. This patient suffered from total bilateral deafness acquired postlingually. The consonants /b/, /p/, /m/, /v/, /f/, /d/, /t/,/n/, /z/, /s/, /g/, /k/ were presented in VCV context with the vowel /a/ as in father by a male and female speaker under three conditions: lipreading alone; electrical stimulation alone using the wearable speech processor and multiple-channel cochlear implant; lipreading in conjunction with electrical stimulation. No significant difference was detected between the results for the male and female speakers. The percentage correct scores for the pooled results of both speakers were lipreading alone - 30%; electrical stimulation alone - 48%; lipreading with electrical simulation - 70%. Performance was significantly better for lipreading with electrical stimulation than for lipreading alone and for electrical stimulation alone than for lipreading alone. An information transmission analysis demonstrated the effective integration of visual and auditory information for lipreading with electrical stimulation. There was a significant improvement in performance for the electrical stimulation alone condition over the 2 months of the study in contrast to no such improvement for lipreading alone.
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ItemParameter selection and programming recommendations for the ACE and CIS speech processing strategies [Abstract]( 1999)The Nucleus 24 Cochlear Implant system with the SPrint processor provides access to multiple speech processing strategies and a wide range of programming parameters. Strategy comparison studies have suggested that the optimal parameter set and coding strategy varies from individual to individual. It is necessary, however, to establish some default programming parameters and fitting guidelines. Therefore we have investigated the effect of stimulation rate and the number of channels or maxima in the ACE or CIS strategies, as well as the optimal programming strategy for subjects with a limited number of available electrodes. Speech perception was tested using monosyllabic words and sentences in noise, with the evaluation protocol designed to take into account learning effects. Take-home experience was provided with all programs, and subjects were asked to complete a comparative performance questionnaire regarding program preference. Six or eight subjects were enrolled in each study.
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