Graeme Clark Collection
Permanent URI for this collection
Search Results
1 - 10 of 13
-
ItemHabilitation issues in the management of children using the cochlear multiple-channel cochlear prosthesis(Wien, 1994)Since 1985, a significant proportion of patients seen in the Melbourne cochlear implant clinic have been children. The children represent a diverse population, with both congenital and acquired hearing-impairments, a wide-range of hearing levels pre-implant, and an age range from 2 years to 18 years. The habilitation programme developed for the overall group must be flexible enough to be tailored to the individual needs of each child, and to adapt to the changing needs of children as they progress. Long-term data shows that children are continuing to show improvements after 5-7 years of device use, particularly in their perception of open-set words and sentences. Habilitation programs must therefore be geared to the long-term needs of children and their families. Both speech perception and speech production need to be addressed in the specific content of the habilitation program for any individual child. In addition, for young children, the benefits of improved speech perception should have an impact on development of speech and language, and the focus of the programme for this age child will reflect this difference in emphasis. Specific materials and approaches will vary for very young children, school-age and teenage children. In addition, educational setting will have a bearing on the integration of listening and device use into the classroom environment.
-
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.
-
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.
-
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.
-
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.
-
ItemPerception of multiple electrode stimulus patterns: implications for design of an electrotactile speech processor( 1991)Abstract not available due to copyright.
-
ItemRole of a multichannel electrotactile speech processor in a cochlear implant program for profoundly hearing-impaired adults( 1991)Four profoundly hearing-impaired adults who did not meet current selection criteria for implantation at the University of Melbourne were each fitted with a wearable multichannel electrotactile speech processor (Tickle Talker). The subjects were evaluated with a test battery of speech discrimination tests subsequent to training in use of the device. Thresholds for detection of pure tones were lower for the Tickle Talker than for hearing aids across the frequency range 250 to 4000 Hz. Mean speech detection thresholds for the Ling 5-sound test showed that all sounds were detected by users of the electrotactile device at normal conversational speech intensity levels. Mean speech discrimination scores were significantly higher (p < 0.05) in the tactually aided condition as compared with the tactually unaided for identification of vowels and consonants, on open-set words, open-set sentences, and on connected discourse tracking. Mean scores increased by 20% for vowels, 19% for consonants, 30% for openset words, and 25% for open-set sentences when the Tickle Talker was used in a multimodal combination with lipreading or lipreading and hearing aids. Speechtracking rates for three subjects showed increases of from 18 to 28 wpm when the tactile device was used. Comparison of tactually aided versus unaided tracking rates for two subjects with long-term experience shows continuing improvement with additional experience with the device. These results demonstrate that hearing impaired adults not meeting selection criteria for cochlear implantation may benefit from use of an electrotactile speech processor, and highlight the potential benefits from integration of such devices into cochlear implant programs for profoundly hearing-impaired patients.
-
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.
-
ItemPerception of sentences, words, and speech features by profoundly hearing-impaired children using a multichannel electrotactile speech processor( 1990)Abstract not available due to copyright.
-
ItemSpeech perception and spoken language in children with impaired hearing( 1998)Fifty seven children with impaired hearing aged 4-12 years were evaluated with speech perception and language measures as the first stage of a longitudinal study. The Clinical Evaluation of Language Fundamentals (CELF) and Peabody Picture Vocabulary Test (PPVT) were used to evaluate the children's spoken language. Regression analyses indicated that scores on both tests were significantly correlated with chronological age, but delayed relative to children with normal hearing. Performance increased at 45% of the rate expected for children with normal hearing for the CELF, and 62% for the PPVT. Perception scores were not significantly correlated with chronological age, but were highly correlated with results on the PPVT and CELF. The data suggest a complex relationship whereby hearing impairment reduces speech perception, which slows language development, which has a further adverse effect on speech perception.