Graeme Clark Collection

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1992 - 1997 6
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Author: Clark, Graeme × Start date: 1990 × Type: Conference Item × Subject: otolaryngology × Subject: otology × Subject: paediatric otology ×

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Now showing 1 - 6 of 6
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    Towards a SSEP hearing screening test for neonates [Abstracts]
    Cone-Wesson, B. ; Parker, J. ; Richards, F. W. ; Ma, E. J. ; Clark, Graeme M. ( 1997)
    Newborn hearing screening tests utilizing evoked otoacoustic emissions (EOAEs) and/or the auditory brainstem response (ABR) recording have been recommended by the NIH(1993). The University of Melbourne experience with steady-state evoked potentials (SSEPs) in newborns suggests that they too, have potential as a screening tool (Rickards et al, 1984). In the present study, SSEPs were recorded from neonates in a pilot study of how the technology may be applied to newborn hearing screening. Eighty-eight neonates were tested using transient-and distortion product EOAEs, ABRs and SSEPs. Only those infants who had TEOAEs, DPOAEs, and ABRs that met a rigid and objective "pass" criteria were included in the study. SSEPs were evoked by amplitude modulated tones using carrier frequencies at 500, 1000, 2000, and 4000 HZ, and modulation frequencies between 75 and 95 Hz presented at levels between 40 and 80 dB SPL. Out of 324 individual SSEP tests, 12% were no-stimulus control trials. Phase-coherence statistics were used to determine when a significant or "passing" result had been obtained. Preliminary results show that a 94% pass rate is achieved for a CF of 2 KHZ, presented at 60 dB SPL, but that pass rates are lower (79% to 89%) for 500, 1KHz and 4KHZ CF's at the same stimulus levels. For lower stimulus levels, pass rates do not exceed 80% for any carrier frequency. Phase-coherence estimates were made for 32, 64, ahd 96 samples at each carrier and modulation frequency combination. We will report the phase coherence estimates for each CF, MF and level combination as a function of sample size, in order to suggest a protocol that may be efficient in newborn hearing screening applications.
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    Psychophysical studies with children using cochlear implants [Abstract]
    Busby, P. ; Blamey, Peter J. ; Tong, Y. ; Clark, Graeme M. ; Dowell, Richard C. ( 1992)
    Psychophysical studies were conducted on a heterogeneous group of 12 patients using, the Cochlear Nucleus cochlear implant. These patients became profoundly deaf early in life, prior to the full development of auditory and speech skills. The aim of the studies was to determine whether the basic hearing skills of these patients differ from those of patients who becamedeaf later in life. The mean age of, the patients at confirmation of the profound hearing loss was 22.3 months (range 6 to 45 months). The mean age of at the time of implantation as 14.8 years (range 5 to 24 years). The cause of deafness was meningitis for 7 patients, congenital Usher's syndrome for 3 patients and congenital unknown for 2 patients.
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    Cochlear implantation in young children: studies on head growth, leadwire design and electrode fixation in the monkey model [Abstract]
    Burton, Martin J. ; Xu, J. ; Shepherd, R. K. ; Xu, S-A. ; Seldon, H. L. ; Franz, B. K-H. G. ; Clark, Graeme M. ( 1992)
    For the safety of cochlear implantation in children under two, the implant assembly must not adversely effect the tissue of compromise head growth. Furthermore, growth changes and tissue responses should not impair functioning of the device. Dummy receiver-stimulators, interconnect plugs and leadwire-lengthening systems have been implanted for periods of 40 months in the young monkey to most effectively model the implantation of the young human child. The results show that implanting a receiver-stimulator package has no effect on skull growth or brain tissue under the package. The system for fixing the electrode at the fossa includes proved effective. There was marked osteoneogenesis in the mastoid cavity and this also resulted in fixation of the leadwire outside the cochlea. This study provides evidence for the safety of cochlear implantation in young children.
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    Cochlear implantation in young children: long-term effects of implantation on the skull and underlying central nervous system tissues in a primate model [Abstract]
    Burton, Martin J. ; Shepherd, R. K. ; Xu, S-A. ; Clark, Graeme M. ( 1992)
    Recent independent studies reporting results obtained by profoundly deaf children implanted with the Melbourne 22-channel cochlear implant have provided further impetus for assessing the feasibility of implanting children under two. Studies in appropriate animal models must first establish the safety of this procedure.
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    Cochlear implantation in young children: long-term effects of implantation on normal hair cells and spiral ganglion cells in the monkey model [Abstract]
    Burton, Martin J. ; Shepherd, R. K. ; Xu, S-A. ; Clark, Graeme M. ( 1992)
    Recent independent results obtained by profoundly deaf children implanted with the Melbourne 22-channel cochlear implant (1) have provided further impetus. for examining thefeasibility of implanting children under two and children with profound deafness. Safety st1,ldies, in appropriate animal models, must first establish the safety of this procedure.
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    Steady-state evoked potentials (SSEPS): an accurate, automated, frequency specific method for objectively assessing hearing thresholds [Abstract]
    Burton, Martin J. ; Rance, G. ; Rickards, Field W. ; Cohen, L. T. ; Clark, Graeme M. ( 1992)
    The determination of hearing thresholds in young children and some adults is impossible using conventional behavioural audiometry. The development of objective methods of assessment for use in such patients is highly desirable.