Graeme Clark Collection
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ItemVowel perception and hearing impairment( 1981)The perception of vowels by young hearing-impaired and normal-hearing children was investigated in two experimental versions, one which required the child ~o make discriminations among minimal pairs, the other which was based on free choice. Each version focused on three lists which comprised monosyllabic real word-pairs whose initial and final consonants were identical. These lists were constructed around high and low frequency components of vowel spectra in order to explore those acoustic aspects which have been hypothesized (Ling, 1978) as being maximally problematic in high-frequency hearing loss. Results indicated that the normal-hearing children, in contrast to the hearing-impaired, made virtually no errors in either task. The hearing-impaired children made significantly more errors in the free-choice task and in the lists whose vowels contained the highest frequency spectra and among those word-pairs which commenced with nonstops.....
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ItemMultiple-channel cochlear implant( 1981)Receiver-stimulator units and multiple electrode arrays were implanted in the scala tympani of one totally deaf patient on 1 August 1978, and one profoundly deaf patient on 17 July 1979. The first patient, a 46 year old male, lost all hearing following a head injury 18 months prior to surgery. Pure tone and speech audiometry showed no hearing in either ear at the maximum output levels of the audiometer, and no vibro tactile responses were elicited. The second patient, a 63 year old male, had a progressive sensorineural hearing loss extended over 30 years due to bomb blast and chronic infection, and had no help from a hearing aide for 13 years prior to surgery. Pure tone audiometry under headphones showed no hearing in the left or operated ear, and in the right he had the following thresholds: 0.125 kHz � 125 db SPL; 0.25 kHz � 115 db SPL and 0.5 kHz � 117 db SPL. There was no speech discrimination in either ear under headphones or in a monitored sound field.
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ItemFrequency discrimination and the spiral ganglion cell population in cats [Abstract]( 1981)Our previous studies on electrical stimulation of the cochlea and auditory nerve have been performed to provide information about cochlear current distributions and electroanatomy, as well as indicating ways of exciting discrete auditory nerve fibre populations to aid in the design of a multiple channel cochlear implant (Black &Clark, 1980). The present study has been carried out to examine the relationship between the size of the spiral ganglion cell population which remains after experimentally-induced graded degeneration of the auditory nerve has occurred and the ability of an animal to perceive certain electrically induced sounds. This is of special interest for a cochlear hearing prosthesis which requires a residual auditory nerve population large enough to adequately relay the electrically induced activity to higher centres.