Graeme Clark Collection
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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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ItemCurrent distribution measurements within the human cochlea( 1981)The magnitudes of tile currents returned through each ground electrode line of a multiple-electrode cochlear implant array were determined during surgical implantations on two patients. These were often found to be distributed widely to points far from the stimulus electrode site. Further measurements made in in vitro solutions demonstrated that the distributions were due largely to the ground electrode interface impedances being significantly larger than the fluid-path impedances, and demonstrated that distributions could be changed by modification of the ground electrode interface impedances.
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ItemPsychophysical and speech perception studies on two multiple-channel cochlear implant patients(Cambridge University Press, 1980)Preliminary studies on our first patient with a multiple channel cochlear implant (Tong et al., 1979) showed that he was able to associate the hearing sensations produced by electrical stimulation of residual auditory nerve fibres with different vowel (spectral) colours. The frequencies characterizing the vowel colours produced by stimulation at single scala tympani electrodes were, in general, closely related to the tonotopical organization of the� cochlea. Furthermore, results from these studies indicated that the pitch produced by single-electrode stimulation increased with pulse rate, and that the loudness increased with current level.
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ItemSpeech processing for a multiple-electrode cochlear implant hearing prosthesis( 1980)Abstract not available due to copyright.
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ItemA preliminary report on a multiple-channel cochlear implant operation(Cambridge University Press, 1979)Intra-cochlear single-channel electrical stimulation has recently been attempted by Michelson (1971) and by House and Urban (1973). Douek et at. (1977) have described experiments with a single-channel promontory electrode system. It is generally accepted that a single-channel system is useful in conveying crude auditory information such as the presence of sounds and some prosodic features of speech (Bilger et al., 1977; Douek et al., 1977). (From Introduction)
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ItemA cochlear implant round window electrode array(Cambridge University Press, 1979)One important aspect of cochlear implantation is the placement of a multiple-electrode array close to residual auditory nerve fibres so that discrete groups of fibres can be stimulated electrically according to the place basis of frequency coding. Furthermore, in patients who are postlingually deaf these electrodes should lie in relation to the nerve fibres which are responsible for transmitting the frequencies which are important in speech comprehension, viz. 300-3,000 Hz. The method of electrode insertion should also ensure that there is no significant damage to auditory nerve fibres.
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ItemA multiple-electrode cochlear implant( 1978)Interest in artificially stimulating the auditory nerve electrically for sensori-neural deafness was first sparked off by Volta in the 18th century. Count Volta, who was the first to develop the electric battery, connected up a number of his batteries to two metal rods which he inserted into his ears. Having placed the rods in his ears he pressed the switch and received "une secousse dans la tete" and perceived a noise like "the boiling of thick soup".
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ItemDesign criteria of a multiple-electrode cochlear implant hearing prosthesis( 1978)Abstract not available due to copyright.
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ItemEngineering(Singular Publishing, 1997)The last two decades have seen major advances in cochlear implants for profoundly deaf people. Implants are now used by severely to profoundly deaf adults and children in almost every phase of daily life. They have become an established treatment, and today's expectations for all aspects of the cochlear implant system are much greater than they were for the experimental devices of the early 1980s. Hardware designs have improved to meet clinical and research demands, technological developments have made the devices smaller and more reliable, and speech processing research has yielded a series of improvements in patient benefit.
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ItemImplant designs for future coding strategies( 1995)This paper briefly describes the history of speech processing developments leading to the presently available Speak processing strategy. The similarities and differences of the Speak and Continuous Interleaved Sampling (CIS) strategies are then discussed and some recent key experimental observations are examined as a guide to potential future coding strategies. Key issues for future coding strategies and implant designs are the number of electrodes and stimulation rates in use. Consideration of these issues has led to development of a prototype implant to be used for advanced speech-processing research.