Graeme Clark Collection

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    Rehabilitation strategies for adult cochlear implant users
    Dowell, R. C. ; Blamey, P. J. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    This paper summarizes open-set speech perception results using audition alone for a large group of adult Nucleus cochlear implant users in Melbourne. The results show wide variation in performance but significant improvement over the years from 1982 to 1995. Analysis of these results shows that speech processor developments have made the major contribution to this improvement over this time. Recent results for patients using the SPECTRA-SPEAK processor show !hat most subjects obtain good speech perception within six months of implantation and the need for intensive auditory training is minimal for many of these patients. Postoperative care should encourage consistent device use by providing opportunities for success and providing long term technical support for implant users. In some cases, including elderly patients, those with long term profound deafness, and those with special needs, there will still be a need for additional rehabilitation and auditory training support.
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    Factors affecting outcomes in children with cochlear implants
    Dowell, R. C. ; Blamey, P. J. ; Clark, Graeme M. (Monduzzi Editore, 1997)
    Open-set speech perception tests were completed for a group of 52 children and adolescents who were long-term users of the Nucleus multiple channel cochlear prosthesis. Results showed mean scores for the group of 32.4% for open-set BKE sentences and 48.1% for phonemes in open-set monosyllabic words. Over 80% of the group performed significantly on these tas1cs. Age at implantation was identified as a significant factor affecting speech perception performance with improved scores for children implanted early. This factor was evident in the results at least down to the age of three years. Duration.. of profound hearing loss, progressive hearing loss, educational program and preoperative residual hearing were also identified as significant factors that may affect speech perception performance.
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    Habilitation issues in the management of children using the cochlear multiple-channel cochlear prosthesis
    Galvin Karyn L. ; Dawson Pam W. ; Hollow Rod. ; Dowell Richard C. ; Pyman B. ; Clark Graeme, M. ; Cowan, Robert S. C. ; Barker, Elizabeth J. ; Dettman, Shani J. ; Blamey, Peter J. ; RANCE, GARY ; Zarant, Julia Z. ( 1993)
    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-impairment, a wide-range or 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 or 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 or 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 selling will have a bearing on the Integration of listening and device use Into the classroom environment.
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    Speech perception, production and language results in a group of children using the 22-electrode cochlear implant
    Busby, P. A. ; Brown, A. M. ; DOWELL, RICHARD ; Rickards, Field W. ; Dawson, Pam W. ; Blamey, Peter J. ; Rowland, L.C. ; Dettman, Shani J. ; Altidis, P. M. ; Clark, Graeme M. ( 1989)
    Paper presented at the 118th Meeting of the Acoustical Society of America
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    Results of multiple-electrode cochlear implants in children
    Tong, Y. C. ; Blamey, P. J. ; Dowell, R. C. ; Nienhuys, T. G. ; Musgrave, G. N. ; Mecklenburg, D. J. ; Busby, P. A. ; Roberts, S. A. ; Dowell, R. C. ; Musgrave, G. N. ; Blamey, P. J. ( 1987)
    Children in Australia and United States of America are now being implanted with the Nucleus 22 electrode intracochlear prosthesis utilizing the F0/F1F2 coding strategy. A total of 32 adolescents (10-17 years) and 24 preadolescents (2-9 years) have been implanted as of 31 August, 1987. No significant postoperative complications were recorded, the speech processors were successfully programmed, and all are users of the device. For the 56 children, the average length of postoperative stimulation time is 2.8 months. Because the majority of children have such short experience with the device we report herein two children from the University of Melbourne (A) and two children from the United States (U) who have been using the Nucleus system for 12 months or more. Child 1A has only 10 electrodes in the cochlea; therefore, the number of channels programmed for the children is 10, 17, 18 and 18, respectively. Child Al and A2 were deafened by meningitis at 3-3 and 3 years of age, respectively. Child U3 became profoundly deafened from a progressive sensorineural loss at age 11 and Child U4 was deafened by recurrent cochlear hydrops at age 13 years.
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    Signal processing in quiet and noise
    Dowell, R. C. ; Patrick, J. F. ; Blamey, P. J. ; Seligman, P. M. ; Money, D. K. ; Clark, Graeme M. ( 1987)
    It has been shown that many profoundly deaf patients using multichannel cochlear implants are able to understand significant amounts of conversational speech using the prosthesis without the aid of lipreading. These results are usually obtained under ideal acoustic conditions but, unfortunately, the environments in which the prostheses are most often used are rarely perfect. Some form of competing signal is always present in the urban setting, from other conversations, radio and television, appliances, traffic noise and so on. As might be expected, implant users in general find background noise to be the largest detrimental factor in their understanding of speech, both with and without the aid of lipreading. Recently, some assessment of implant patient performance with competing noise has been attempted using a four-alternative forced-choice spondee test (1) at Iowa University. Similar testing has been carried out at the University of Melbourne with a group of patients using the Nucleus multichannel cochlear prosthesis. This study formed part of an assessment of a two formant (F0/FI/F2) speech coding strategy (2). Results suggested that the new scheme provided improved speech recognition both in quiet and with competing noise. This paper reports on some more detailed investigations into the effects of background noise on speech recognition for multichannel cochlear implant users.
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    A formant-estimating speech processor for cochlear implant patients
    Blamey, P. J. ; Dowell, R. C. ; Brown, A. M. ; Seligman, P. M. ; Clark, Graeme M. (Speech Science and Technology Conference, 1986)
    A simple formant-estimating speech processor has been developed to make use of the "hearing" produced by electrical stimulation of the auditory nerve with a multiple-channel cochlear implant. Thirteen implant patients were trained and evaluated with a processor that presented the second formant frequency, fundamental frequency, and amplitude envelope of the speech. Nine patients were trained and evaluated with a processor that presented the first formant frequency and amplitude as well. The second group performed significantly better in discrimination tasks and word and sentence recognition through hearing alone. The second group also showed a significantly greater improvement when hearing and lipreading was compared with lipreading alone in a speech tracking task.
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    Psychophysics of multiple-channel stimulation
    Dowell, R. C. ; Tong, Yit. C. ; Blamey, P. J. ; Clark, Graeme M. (Raven Press, 1985)
    Eight patients implanted with multiple-channel cochlear prostheses have displayed good discrimination of sound sensations elicited at different sites within the cochlea. All patients rank the sensations from "sharp" to "dull" in an order which corresponds with basal to apical position in the cochlea. Detailed psychophysical studies have been carried out on two patients. These showed that discrimination of rate of (pulsatile) stimulation is good for frequencies up to 300 Hz and falls off sharply for frequencies above this. Electrode transitions (changes in position along the cochlea) are well discriminated for fast changes (25 msec), whereas rate transitions are not well discriminated for changes faster than 100 msec. From these results a speech processing strategy was formulated where second formant information is mapped to position in the cochlea and fundamental frequency mapped to rate of stimulation. Vowel and consonant confusion studies show consistent results for all patients using this processing strategy. A study involving two electrode stimuli demonstrated the possibility of presenting first formant information in addition to the second formant and fundamental frequency.