Graeme Clark Collection
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ItemAcquisition of a tactile-alone vocabulary by normally hearing users of the Tickle Talker( 1999)Abstract not available due to copyright.
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ItemA modification of play audiometry to assess speech discrimination ability in severe-profoundly deaf 2- to 4-year-old children( 1998)Objective: The aim was to develop an assessment procedure that was independent of language and speech production ability, to test speech feature discrimination severe-profoundly deaf children 2 to 4 yr of age. Design: The procedure being trialled was adapted from existing procedures. The child was required to respond with a game-like motor response to a “change” in a speech stimulus that was being presented repeatedly through a speaker. The change occurred at randomly determined times, and false alarm responses were measured during the waiting periods (while the child waited for the change). Two- to four-yr-old normally hearing children and hearing-impaired children using hearing aids and a group of 4-yr-old hearing-impaired children using cochlear implants were assessed on the task. Results: More than 82% of the 3- and 4-yr-old normally hearing and hearing-impaired children were able to complete the testing for the eight speech sound contrasts within three 20 minute sessions. Fifty percent of the 2-yr-old normally hearing and hearing-impaired children were able to condition and complete the task. All of the normally hearing children who completed the task successfully discriminated all speech sound contrasts. The performance of the hearing-impaired children using hearing aids was influenced by the degree of hearing loss and the type of speech contrast being tested. Similarly, the average performance of the children using cochlear implants was better for easier contrasts such as /ba/bi/ with contrasting vowel formant cues. Conclusions: This procedure has potential for use as a reliable clinical and research tool for assessing the development of auditory discrimination ability in 2- to 4-yr-old severe-profoundly deaf children.
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ItemA comparison of Tactaid II+ and Tactaid 7 use by adults with a profound hearing impairment( 1999)Objective: To evaluate and compare use of the Tactaid II+ and the Tactaid 7, in terms of speech perception, by adults with a hearing impairment. Design: Eight adults used one device daily for approximately 10 wk and attended seven training sessions. Performance was measured with tests of phonetic contrast perception, closed-set vowel and consonant identification, word and phoneme recognition in monosyllabic word lists, word recognition in sentences and speechtracking rate. A questionnaire was also administered. The protocol was repeated with the alternative device. Results: With each device, the group discriminated most phonetic contrasts at better-than-chance levels and demonstrated somewhat enhanced visual or auditory-visual perception when measured in terms of vowel identification, monosyllabic word recognition and speechtracking rate. An increase in speechtracking rate was also demonstrated for some individuals. Subjects generally reported little subjective improvement in speech perception and production, but were satisfied with the physical attributes of each device. Five of six subjects preferred the Tactaid 7. Conclusions: The Tactaid II+ and the Tactaid 7 provided suprasegmental and segmental information, enabling the group to discriminate phonetic contrasts and improve their perception of some speech materials. No consistent advantage was found for either device, thought most subjects preferred the Tactaid 7. Alternatives likely to provide a greater benefit to communication should be considered before Tactaid fitting.
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ItemA clinical report on speech production of cochlear implant users( 1995)Objective: The aim was to assess articulation and speech intelligibility over time in a group of cochlear implant users implanted at 8 yr or over. The hypothesis was that the postoperative speech production performance would be greater than the preoperative performance. Design: A test of intelligibility using sentences and an articulation test measuring non-imitative elicited speech were administered to 11 and 10 subjects, respectively, who were implanted with the 22-electrode cochlear implant. Nine subjects received both tests. Age at implantation ranged from 8 yr to 20 yr and implant use ranged from 1 yr to 4 yr 5 mo. Results: For both the intelligibility and articulation tests roughly half of the subjects showed significant improvements over time and group mean postoperative performance significantly exceeded preoperative performance. Improvements occurred for front, middle, and back consonants; for stops, fricatives, and glides and for voiceless and voiced consonants. Conclusions: Despite being deprived of acoustic speech information for many childhood years, roughly half of the patients assessed showed significant gains in speech intelligibility and articulation postimplantation. The lack of a control group of non-implanted patients means that we cannot separate out the influence of the implant on speech production from other influences such as training and tactile-kinaesthetic feedback.
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ItemThe progress of children using the multichannel cochlear implant in Melbourne( 1995)Multi-channel cochlear implantation in children began in Australia in 1985 and there are now close to 4000 profoundly deaf children and adolescents using the Australian implant system around the world. The aim of the implant procedure is to provide adequate hearing for speech and language development through auditory input. This contrasts with the situation for adults with acquired deafness where the cochlear implant aims to restore hearing for someone with well-developed auditory processing and language skills. As with adults, results vary over a wide range for children using the Multi-channel implant. Many factors have been suggested that may contribute to differences in speech perception for implanted children. In an attempt to better understand these factors, the speech perception results for children implanted in Melbourne were reviewed and subjected to statistical analysis. This has indicated that the amount of experience with the implant and the length of sensory deprivation are strongly correlated with perceptual results. This means that younger children are likely to perform better with an implant and that a number of years of experience are required for children to reach their full potential. The results have also indicated that educational placement and management play a crucial role in children reaching their potential. Overall, 60% of the children and adolescents in the study have reached a level of open-set speech understanding using the cochlear implant without lipreading.
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ItemA review of the biological, psychophysical, and speech processing principles used to design the tickle talker( 1992)The Tickle Talker is a wearable electrotactile speech processor, designed to be used by profoundly hearing-impaired children and adults in conjunction with lipreading and residual hearing. The effectiveness of such a device is affected by an interaction between biological, human engineering, psychophysical, and speech processing considerations. The requirements, the design principles, and the performance of the Tickle Talker in each of these areas will be discussed. Electrical stimulation of the nerve bundles lying along the sides of the fingers was chosen to provide safe, comfortable, energy-efficient stimulation of a well-organised and sensitive part of the tactile sensory system. This is achieved at a small cost to the appearance and mobility of one hand when using the Tickle Talker. The biphasic pulse waveform used to stimulate the nerve bundles has been chosen to ensure a biologically safe stimulus. The electrical parameters (pulse duration, pulse rate, and electrode position) that are used to encode speech information are varied within ranges that are matched to the characteristics of the tactile sense. The usable ranges and information-carrying potential of each of these parameters have been assessed in psychophysical experiments. A comparison of these results with similar experimental data for cochlear implant and hearing aid users is instructive in assessing the possible limitations of tactile and auditory speech processors. The results discussed will include the discrimination and identification of stimuli differing in intensity, duration and pulse rate; the identification of different spatial patterns of stimulation, and the detection of gaps in stimuli. In most respects, the tactile results are similar to the corresponding auditory measures. The resolution of temporal differences such as pulse rate discrimination or gap detection are generally not as good as in the auditory case, but may be as good or better than the corresponding results for some profoundly hearing-impaired individuals. The speech processor used in the Tickle Talker is a "feature extraction" device that explicitly estimates the second formant frequency, amplitude envelope, and fundamental frequency of the voice and encodes them in terms of electrode position, pulse width and pulse rate of the electrical stimulation pattern. Consideration of the psychophysical results and the speech information available from these parameters allows optimization of the Tickle Talker's operation and a broad estimation of its potential performance in speech discrimination. The perception of duration and place of articulation (front/back) of vowels, and the manner and voicing of consonants are expected to be improved by the Tickle Talker. Prosodic variations conveyed by pulse rate are expected to be perceived by some users, but not all. High frequency consonants such as: /s/,/z/./?/, and /t?/ are encoded in a particularly salient manner by the Tickle Talker.
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ItemClinical experience with the University of Melbourne multichannel electrotactile speech processor (Tickle Talker)( 1992)The Tickle Talker is a multiple channel electrotactile speech processor, developed for use by profoundly hearing-impaired adults and children. The device is intended to be used in combination with lipreading and aided residual hearing, to assist the greatest potential range of users. Sound detection and speech reception threshold levels for a group of 14 congenitally hearing-impaired children were shown to be lower when using the Tickle Talker than for hearing aids across the speech frequency range. Tactile-alone feature contrast testing with adults demonstrated that both segmental and suprasegmental speech feature information was available from the tactual display presented by the Tickle Talker. Clinical results from an ongoing program involving fourteen hearing-impaired children demonstrate benefits in speech perception achieved through use of the Tickle Talker. The children have a range of degree of hearing impairment and educational setting. Results show improvements in discrimination scores for vowel and consonant speech features, and increased scores for recognition of closed-set words and for open-set words and sentences. In addition, anecdotal evidence indicates changes in speech production which may be attributed to perceptual input from the device (both from perception of other speakers, and from voice self-monitoring). Results from a group of 4 adult patients show that tactile input may be effectively combined with either aided residual hearing, or aided residual hearing and lipreading to improve speech discrimination across a similar range of closed and open-set word and sentence tests and on speech tracking. The results indicate that some specific tailoring of the speech information provided through the device for the needs of users with differing degrees of hearing-impairment may be required to optimize potential benefits to speech discrimination.
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ItemFactors in the development of a training program for use with tactile devices( 1993)A review of the literature suggests that, in order to maximize the benefits available through a tactile device, it must be accompanied by an effective and adaptive training program. There are a number of factors to consider in the design of such a training program, including the type of tasks and response formats to include, the amount of training, subject motivation and device use, the characteristics of the potential user population, the specific device to be used and the type of information it provides, and the evaluation procedures to be followed. The type and saliency of the information provided by a particular tactile device are highlighted as the most important yet neglected consideration in designing a training program. The training program used with the University of Melbourne’s multiple-channel electrotactile device is presented to show how these important factors may be addressed, to indicate the flexibility required in a training program, and to provide a general framework on which researchers may base the development of programs for other tactile devices.
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ItemCochlear implants in children, adolescents, and prelinguistically deafened adults: speech perception( 1992)A group of 10 children, adolescents, and prelinguistically deafened adults were implanted with the 22-electrode cochlear implant (Cochlear Ply Ltd) at the University of Melbourne Cochlear Implant Clinic and have used the prosthesis for periods from 12 to 65 months. Postoperative performance on the majority of closed-set speech perception tests was significantly greater than chance, and significantly better than preoperative performance for all of the patients. Five of the children have achieved substantial scores on open-set speech tests using hearing without lipreading. Phoneme scores in monosyllabic words ranged from 30% to 72%; word scores in sentences ranged from 26% to 74%. Four of these 5 children were implanted during preadolescence (aged 5:5 to 10:2 years) and the fifth, who had a progressive loss, was implanted during adolescence (aged 14:8 years). The duration of profound deafness before implantation varied from 2 to 8 years. Improvements were also noted over postoperative data collection times for the younger children. The remaining 5 patients who did not demonstrate open-set recognition were implanted after a longer duration of profound deafness (aged 13:11to 20:1 years). The results are discussed with reference to variables that may affect implant performance, such as age at onset of loss, duration of profound loss, age at implantation, and duration of implantation. They are compared with results for similar groups of children using hearing aids and cochlear implants.
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ItemUse of a multichannel electrotactile speech processor by profoundly hearing-impaired children in a total communication environment( 1991)As part of a larger subject group, four profoundly hearing-impaired children enrolled in a total communication educational program were fitted with the University of Melbourne's multichannel electrotactile speech processor (Tickle Talker). Sound detection thresholds for pure tones were at lower levels with the tactile device than with hearing aids, especially for high frequency sounds above 2 kHz. Two of the children also detected all speech sounds of the Ling five-sound test at normal conversational levels using only the Tickle Talker. The children were able to use tactile input to achieve higher scores on three speech feature subtests of the PLOTT test when using the Tickle Talker plus hearing aids as compared to hearing aids alone. Mean improvements were 22.4 percent on vowel length, 28 percent on vowel identification, and 35 percent on consonant manner. Improvements were also shown by individual children on the closed-set WIPI and open-set PBK word tests, and on the open-set BKB sentence test, when the Tickle Talker was combined with hearing aids, and with hearing aids and lipreading. Comparisons of these results with those of children using the Tickle Talker in other educational settings show that children in a total communication environment can potentially benefit to a similar degree from use of tactual input. Anecdotal reports from the children and school staff members indicated that daily use of the Tickle Talker did not interfere with the signing aspects of total communication.