Graeme Clark Collection
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ItemA clinical report on vocabulary skills in cochlear implant users [Abstract]( 1994)Receptive vocabulary results are reported for 32 children, adolescents and prelinguistically deafened adults implanted with the 22-electrode cochlear implant at the Melbourne Cochlear Implant Clinic. Age at implantation ranged from 2 years, 6 months to 20 years and implant use ranged from 1 year to 7 years, 8 months. There were significant gains from pre- to postoperative assessments on the Peabody Picture Vocabulary Test (PPVT) for the majority of subjects. Rates of improvement found are compatible with previous reports on smaller numbers of implant users, but cannot be attributable unambiguously to use of the implant. The group postoperative performance was significantly higher than mean preoperative performance (n =25). The relationship of variables such as duration of implant use, duration of profound deafness and speech perception ability to improvement on the PPVT is discussed. Expressive vocabulary results on the Renfrew Word Finding Vocabulary Scale are reported for 11 of the subjects. Less substantial gains were made on this measure.
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ItemIssues in long-term management of children with cochlear implants and tactile devices [Abstract]( 1994)For many children with severe and profound hearing losses, conventional hearing aids are unable to provide sufficient amplification to ensure good oral communication and/or in the case of very young children, development of speech and language. Traditionally a number of these children have opted for the use of sign language alone or in Total Communication approaches as a primary means of communication. The advent of multiple channel cochlear implants for children and the continuing development of multiple channel speech processing tactile devices provide auditory approaches to resolving communication difficulties for these children. The successful use of such devices depends on a number of factors including the information provided through the aid; the ease of use, convenience and reliability of the aid; the individual communication needs of the child; and the habilitation and management program used with the device. Long-term data has shown that children continue to show increased speech perception benefits from improvements in speech processing and from further experience with these devices. Habilitation and management programs must therefore be geared to meet the changing needs of children as they progress and of families as children mature and face new challenges. Habilitation must address specific individual needs in speech perception and in speech production. For very young children, benefits of improved speech perception should have an impact on the development of speech and language, and habilitation and management must emphasise the need for language growth.
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ItemA clinical report on speech production of cochlear implant users [Abstract]( 1994)Speech production results are reported for a group of 15 children, adolescents and prelinguistically deafened adults implanted with the 22-electrode cochlear implant. Age at implantation ranged from 5 years to 20 years and implant experience ranged from 1 year to 4 years, 7 months. On a speech intelligibility test using sentences seven implant users improved significantly over time. Mean group performance (n = 11) improved from 18% preoperatively to 43% postoperatively. Similarly on a test of articulation, eight implant users improved significantly over time and the group mean postoperative performance (n = 11) exceeded the preoperative performance (55% compared to 38%). This group effect was significant for consonants and blends but was nonsignificant for vowels. Improvements occurred for front, middle and back consonants, for stops, nasals, fricatives and glides and for voiceless and voiced consonants. Three implant users showed no significant gain on either test. The results suggest complex relationships between speech production performance and sensory information provided by a multichannel implant.
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ItemDesign fundamentals for a tactile speech processor: i) encoding of speech information, and ii) biomedical safety considerations [Abstract]( 1992)Approaches to providing speech information through the tactual modality have varied in: number and spatial location of transducers; method of interfacing with the skin's sensory apparatus; and content of speech information presented. Use of a multiple speech feature encoding approach to design of a tactile device was implemented in the wearable multichannel electrotactile speech processor or Tickle Talker developed at the University of Melbourne. Psychophysical studies established that subjects could discriminate salient electrical parameters in the tactual display, and that this information could be used to discriminate acoustic speech feature contrasts. Results with normally-hearing and hearing-impaired adults and children using an FOF2 encoding strategy showed improved discrimination scores for closed-set speech feature discrimination batteries, closed-set vowel and consonant identification tasks, as well as for open-set word and sentence comprehension. Based on analyses of tactual encoding of speech features, alternative speech processing strategies designed to increase the quality of speech information available were evaluated. Results for two hearing-impaired adults showed improved feature discrimination with the addition of a voicing signal to the FOF2 strategy. Biomedical safety investigations conducted concurrently have established that the electrical parameters of the stimulus waveform, electrode handset design, and electrical circuitry of the device are free from potential risks. Longer-term physiological assessments included measures of possible effects of electrical stimulation on tactual sensitivity, finger temperature, finger and hand blood flow, electrical thresholds and maximum comfortable levels, and on central nervous system, function as measured by EEG. Results of the kinesthetic, vascular and neurological assessments showed no significant contraindications which might limit application or long-term use of the device.
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ItemSpeech feature encoding through an electrotactile speech processor [Abstract]( 1989)Abstract not available due to copyright.
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ItemThe Tickle Talker: a speech perception aid for profoundly hearing impaired children [Abstract]( 1990)Fifteen prelingually profoundly hearing-impaired children participated in speech perception training and evaluation, to assess potential benefits from use of the Tickle Talker. This device, a multichannel electrotactile speech processor, developed by Cochlear Pty. Ltd. and the University of Melbourne, presents speech as a pattern of electrical sensations felt on the fingers. The eight small electrodes are located over the digital nerve bundles, on both sides of the four fingers of the non-dominant hand. Speech processing hardware is similar to that used in the 22-channel cochlear implant. In the encoding strategy, second formant frequency (F2) is presented as electrode position, speech waveform amplitude as stimulus strength, and fundamental frequency (FO) as rate of stimulation. Each child participated in an ongoing training program involving clinicians, teachers and parents. The evaluation program included measures of sound and speech detection thresholds, and discrimination of speech features, words and open-set sentences. Both individual and mean scores for all the children demonstrate significant improvements in speech perception scores when input from the Tickle Talker is combined with either aided-residual hearing, or aided residual hearing and lipreading. These results are consistent with those previously reported for profoundly hearing-impaired adults using the Tickle Talker, and indicate that children are able to integrate speech information provided through the tactual modality with information from vision or residual hearing.
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ItemSpeech feature recognition by profoundly deaf children using the University of Melbourne multichannel electrotactile aid [Abstract]( 1989)Abstract not available due to copyright.
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ItemPreliminary evaluation of a wearable multichannel electrotactile speech processor [Abstract]( 1988)Speech discrimination testing, using both open-and closed-set materials was carried out with four severely-to-profoundly hearing impaired adults. and seven normally hearing subjects, to assess performance of a wearable eight-channel electrotactile aid (Tickle Talker). The device consisted of a handset composed of nine electrodes, a stimulator-unit, and a speech processor and input microphone. Eight small electrodes were located over the digital nerve bundles on each side of the four fingers of one hand, and a larger common electrode was placed on the wrist. Subjects perceived eight separate channels of information, each corresponding to a stimulus on one side of one finger. The speech processor provided estimates of second formant frequency, fundamental frequency and amplitude of the speech waveform. These features were coded as electrode position, pulse rate and pulse width respectively. This processing strategy (FOF2AO) is similar to that used in an earlier model of the Cochlear Pty. Ltd. cochlear implant.
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ItemEvaluation of training strategies with an electrotactile speech processor [Abstract]( 1988)During 1986, seven normally-hearing subjects were trained in the use of an electrotactile speech processor ("Tickle Talker"). Two training methods were used: (a) a combined strategy. in which a variety of training materials ranging from analytic to synthetic level were employed; and (b) a synthetic alone training strategy, in which only synthetic level training materials were used. All seven subjects received 70 hours of training, 35 hours in each training strategy. Subjects were evaluated in the tactile-lipreading (TL) and lipreading alone (L) conditions at: (I) 0 hours training; (2) 35 hours training; and (3) after 70 hours of training. An evaluation test battery was constructed which contained both closed-set and open-set materials. Results indicated differences in performance on the evaluation tests which were dependent upon the training strategy. The differences in performance were greater in some evaluation tests than others. Subsequently; seven severe-profoundly hearing-impaired children (aged 7-11) have been fitted with the Tickle Talker and are presently participating in an ongoing training programme. Evaluation of their performance will help to assess the suitability of the device for young children.
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ItemStudies in tactile speech perception using the University of Melbourne Tickle Talker [Abstract]( 1998)During the past four years, a series of studies have been undertaken investigating the perception of speech presented through the tactile modality. These studies formed part of a project to develop an effective and safe electro tactile speech perception device for those children and adults requiring additional communication assistance to that provided by hearing aids, but unable to benefit from cochlear implants.