Graeme Clark Collection
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ItemElectrode discrimination and speech perception in young children using cochlear implants( 2000)Objective: The aim was to determine the efficacy of a child-appropriate procedure to assess electrode discrimination ability in young children using cochlear implants and to investigate the relationship of electrode discrimination ability and speech perception performance in children implanted at a young age. Design: An adaptation of the play audiometry procedure was used to assess electrode discrimination in seventeen 4- to 10-yr-old children. The children were required to respond with a game-like motor response when a repeating stimulation on a reference electrode “changed” to a different electrode. They were also assessed on a speech feature discrimination test, a closed-set word recognition test and a nonverbal intelligence task. Results: Sixty-five percent of subjects demonstrated ability to discriminate adjacent electrodes in mid and apical regions of the cochlea, whilst the remaining subjects needed electrode separations of between two and nine electrodes for successful discrimination. In a forward stepwise regression analysis electrode discrimination ability was found to be the strongest factor in accounting for variance in the speech perception scores. Subject variables such as duration of deafness, nonverbal intelligence and implant experience did not significantly account for further variance in the speech perception scores for this group of children. Conclusions: Electrode discrimination ability was the strongest factor in predicting performance on speech perception measures in a group of children using cochlear implants.
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ItemThe development of the Melbourne/Cochlear multiple-channel cochlear implant for profoundly deaf children( 1992)In 1978-79, a speech processing strategy which extracted the voicing (FO) and second formant (F2) frequencies and presented these as rate and place of stimulation respectively to residual auditory nerve fibres was developed for the University of Melbourne's prototype multiple-channel receiver-stimulator (Clark et aI1977, Clark et a11978, Tong et aI1980). This speech processing strategy was shown to provide post linguistically deaf adults with some open-set speech comprehension using electrical stimulation alone, and considerable help when used in combination with lipreading (Clark et al 1981).
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ItemSpeech perception, production and language results in a group of children using the 22-electrode cochlear implant( 1992)Five children out of a group of nine (aged 5.5 to 19.9 years) implanted with the 22-electrode cochlear implant (Cochlear Ply. Ltd.) have achieved substantial scores on open-set speech tests using hearing without lipreading. Phoneme scores for monosyllabic words ranged from 40% to 72%. Word scores in sentences ranged from 26% to 74%. Four of these five children were implanted during preadolescence. The fifth child, who had a progressive loss and was implanted during adolescence after a short period of very profound deafness, scored highest on all speech perception tests. The remaining four children who did not demonstrate open-set recognition were implanted during adolescence after a long duration of profound deafness. Post-operative performance on closed-set speech perception tests was better than pre-operative performance for all children. Improvements in speech and language assessments were also noted. These improvements tended to be greater for the younger children. The results are discussed with reference to variables which may contribute to successful implant use: such as age at onset, duration of profound hearing loss, age at implantation, aetiology, educational program, and the type of training provided.
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ItemThe perception of vowels by hearing impaired children [Abstract]( 1982)This paper reports the results of a series of closed-set vowel identification experiments with four congenitally hearing impaired children (age 13 years) with moderate to profound bilateral sensorineural losses. Material was presented under three test conditions: hearing alone, through currently worn hearing aids; lipreading alone; and hearing plus lipreading. Analysis of the results using multidimensional scaling and hierarchical clustering revealed a strong relationship between the perceptual organisation of the responses and the physical attributes of the method of signal presentation. In the case of acoustic signals, the results indicated a perceptual organisation describable in terms of the duration of the vowel and the relative frequencies of the first and second formant. For visual signals, the perceptual organisation correlated with characteristics of lip-shaping during production. These results indicated that the subjects attempted to use similar perceptual cues as the normally hearing population. The relationship between the perceptual organisation of the acoustic stimuli and the aided audiogram is also discussed.
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ItemAuditory processing abilities in children using cochlear implants: their relevance to speech perception [Abstract]( 1999)This study aimed to investigate the relationships between some basic auditory processing skills, subject variables and speech perception ability in young children using cochlear implants. A modification of the play audiometry procedure was used to measure electrode discrimination and "rate-of-processing" ability in seventeen 4-10 year old children. In the electrode discrimination task, children responded with a game-like motor response when a repeating stimulation on a reference electrode "changed" to a different electrode. In the "rate-of processing" task, children had to respond to the "change" to a different electrode, when the duration of the stimuli and the time interval between the stimuli were decreased. Normally hearing children were assessed on this task with acoustic stimulation. Nonverbal intelligence, speech feature discrimination and closed-set word recognition were also measured in the children using implants.
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ItemPsychophysical studies with children using cochlear implants [Abstract]( 1992)Psychophysical studies were conducted on a heterogeneous group of 12 patients using, the Cochlear Nucleus cochlear implant. These patients became profoundly deaf early in life, prior to the full development of auditory and speech skills. The aim of the studies was to determine whether the basic hearing skills of these patients differ from those of patients who becamedeaf later in life. The mean age of, the patients at confirmation of the profound hearing loss was 22.3 months (range 6 to 45 months). The mean age of at the time of implantation as 14.8 years (range 5 to 24 years). The cause of deafness was meningitis for 7 patients, congenital Usher's syndrome for 3 patients and congenital unknown for 2 patients.