Graeme Clark Collection

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    Inner ear implants
    Clark, Graeme M. (Dekker, 2004)
    The cochlear implant is an electronic device that brings useful hearing to severely to profoundly deaf people through multiple-channel electrical stimulation of the auditory nerves in the inner ear. This is required if their inner ears are so badly damaged by injury and disease, or so inadequately developed, that they cannot provide sufficient hearing for communication, even when the sound is amplified with a hearing aid. By stimulating the nerve directly with patterns of electrical pulses, the implant bypasses the normal function of the sense organ of hearing in the inner ear to partially reproduce the coding of sound. It consists of a wearable speech processor that picks up sound with a microphone, analyzes the signal, and then sends it by radio waves to the implanted receiver stimulator, which decodes the message and stimulates the electrode wires inserted into the inner ear.
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    Validation of a technique for establishing maximum comfortable levels for children using cochlear implants [Abstract]
    Hollow, R. ; Winton, L ; Hill, K. ; Dowell, R. ; Clark, Graeme M. ( 2002)
    The aim of fitting a cochlear implant is to establish electrical stimulation parameters that will provide the wearer with comfortable and useful auditory sensations. One parameter that is fundamental to achieving this aim is the Maximum Comfortable Level (C-level). A C-level is the amount of electrical current that produces a loud, but comfortable sound. C-levels need to be established for all channels that a person will use in their speech processor Map. Determining C-levels can be complicated as the person is required to make a judgment about the loudness of a sound. While most adults and older children have the ability to make such a judgment and provide feedback to the clinician, this is rarely the case for young children. Generally, the only way a clinician will be aware a sound could be too loud for a young child is when they observe the child giving an aversive reaction or an involuntary blink. A current level that produces such a reaction is called the Loudness Discomfort Level (LOL). This study examines the relationship between LDLs and C-levels. Testing was performed with a group of adults, using stimulation rates and stimulation modes that are commonly used by children. The LDL/C-level relationship established in this study provides a procedure for selling C-Levels for young children when only loudness discomfort responses can be obtained.
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    Physiological and histopathological effects of chronic monopolar high rate stimulation on the auditory nerve
    TYKOCINSKI, MICHAEL ; Linahan, N. ; Shepherd, R. K. ; Clark, Graeme M. ( 2000)
    Speech processing strategies based on high rate electrical stimulation have been associated with improvements in speech perception among cochlear implant users. The present study was designed to evaluate the electrophysiological and histopathological effects of long-term intracochlear monopolar stimulation at the maximum stimulus rate of the current Nucleus Cochlear implant system (14493 pulses/s) as part of our ongoing investigations of safety issues associated with cochlear implants