Graeme Clark Collection
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ItemThe effects of electrode position and stimulus period on the hearing sensations in a multiple-channel cochlear implant patient [Abstract]( 1981)Abstract not available due to copyright.
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ItemPerceptual dissimilarity and discrimination studies using two-electrode stimulation with a multiple-channel cochlear implant patient [Abstract]( 1981)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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ItemModeling studies on current distributions produced by an intracochlear electrode array [Abstract]( 1986)Abstract not available due to copyright.
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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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ItemEvoked responses in humans to continuous amplitude modulated tones [Abstract]( 1982)The clinical use of the slow cortical auditory evoked responses and the auditory brainstem response is now widespread. Both of these responses look at the electrical changes in the brain following the onset of an acoustic stimulus and are known as transient responses. This paper will describe a technique of recording electrical potentials evoked during a continuous sinusoidally-modulated amplitude-modulated tone. This type of response is known as a steady-state response. The responses to this type of sound were found to be periodic, having the same fundamental frequencies as the modulation envelope. A Fourier transform was used to quantify the amplitude and phase of the first two harmonic components of the response. Responses can be recorded for modulation rates from 4Hz to 448Hz, for carrier frequencies from 250Hz to 4KHz and for sound pressure levels (SPLs) from 30dBSPL to 100dBSPPL. In general, the response amplitude increases with SPL. Estimates of latencies of these steady-state potentials can be made by measuring the phase of both harmonics as the modulation frequency is varied. Latencies suggest the auditory cortex as one of the sources of the response. The clinical implication of these results will be discussed.
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ItemImplants aid hearing( 1982)In August 1978 surgeons from the University of Melbourne carried out a cochlear implant operation at the Royal Victorian Eye and Ear Hospital on a totally deaf patient who had lost all hearing following a head injury. The operation involved inserting an array of 20 separately insulated electrode wires along the fluid-filled scala tympani of the inner ear and then implanting an attached receiver-stimulator device in the mastoid bone behind the ear.
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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.