Graeme Clark Collection
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ItemThe perception of electrodes by cochlear implant patients who became deaf early in life [Abstract]( 1994)Two separate studies measuring the perception of differences in site of electrode stimulation were conducted with cochlear implant patients who became deaf early in life. The multiple-electrode prosthesis manufactured by Cochlear Pty. Limited was used. Two of the possible mechanisms for the discrimination of different electrodes are pitch and loudness. The first study measured the discrimination of different electrodes using two procedures which minimised the influences of loudness cues on performance. In the first procedure, the stimulation patterns were symmetric sweeps across electrodes. The reference stimuli were apical-basal trajectories and the comparison stimuli were basal-apical trajectories. The electric stimulation levels were the same in the reference and comparison stimuli because the same electrodes were used in the trajectories. In the second procedure, the stimulation patterns used randomised variations in electric stimulation levels on the different electrodes. By randomly varying the loudness of the stimuli in a discrimination task, the patient is required to listen for more salient cues such as pitch. Both procedures gave comparable results. The second study was concerned with the estimation of order in percepts for stimulation on the different electrodes along the array which was related to the tonotopic order of the cochlea. Approximately half of the early-deafened patients tested revealed a tonotopic order in percepts which was comparable to that obtained from postlinguistically deafened adults.
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ItemDiscrimination of electrical trajectories by cochlear implant patients [Abstract]( 1990)Abstract not available due to copyright.
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ItemResults in children using the 22 electrode cochlear implant [Abstract]( 1989)Abstract not available due to copyright.
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ItemPsychophysical studies on cochlear implant patients deafened prior to 4 years of age [Abstract]( 1989)Abstract not available due to copyright.
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ItemVowel and consonant perception by pre-lingual subjects using a Multiple electrode cochlear implant [Abstract]( 1986)Two speech perception experiments were conducted on three pre-lingually deaf subjects (deafened before 16 months of age), two adults and one adolescent, within the first year of use of multiple electrode cochlear implant. First was vowel identification in the electrical stimulation alone (E), vision alone (V), and electrical stimulation plus vision (EV) conditions. Second was consonant identification in the E, V, and EV conditions. To reveal the underlying structures of the perceptual confusions, data for the first experiment were analyzed using multidimensional scaling, and data for the second using hierarchical clustering and information transmission analysis. The one-dimension solution for vowels in the E condition was interpreted as vowel length. Visual vowel parameters interpreted the one dimension solution for the V condition and two-dimension solution for the EV condition. The E condition consonant results indicated a high degree of perceptual confusion. The minimal differences between the consonant results for the V and EV conditions suggested minor influences of the electrical signal in EV perception. The results were in agreement with the psychophysical data obtained from the subject. These findings suggested that the subjects were unable to effectively use all the information provided by the multiple electrode cochlear implant during the first year.
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ItemA clinical protocol for multiple electrode cochlear implants in children [Abstract]( 1986)A clinical protocol for an experimental study to evaluate the speech perception and production, and communication skills using the multiple electrode cochlear implant in pre-adolescent children has been developed. A single-subject time-series design has been adopted to regularly assess these abilities. During the pre-operative stage the subject's current hearing aids or tactile device are used, and for the post-operative stage the Nucleus multiple electrode intracochlear implant. Training is provided in both stages of the study. Also included in the pre-operative stage are the audiological and medical evaluations to determine whether the subject meets the selection criteria. Speech perception and production, and communication skills are assessed from a large selection of language and developmental-age appropriate materials. Psychophysical studies are also undertaken to measure the subject's abilities to discriminate simple stimuli differing in electrical parameter values.
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ItemPsychophysical studies on prelingual patients using a multiple-electrode cochlear implant [Abstract]( 1986)Abstract not available due to copyright.
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ItemSpeech perception studies in the first year of usage of a multiple electrode cochlear implant by prelingual deaf patients [Abstract]( 1986)Abstract not available due to copyright.
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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.