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KMID : 0858620020060020111
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Korean Journal of Audiology
2002 Volume.6 No. 2 p.111 ~ p.113
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Effects of Differential Stimulus Levels on Electrically Evoked Auditory Responses
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Lim Duk-Hwan
Kim Chong-Sun
Chang Sun-O
Oh Seung-Ha
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Abstract
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Different types of electrode arrays and coding strategies have been used to aid speech intelligibility in cochlear implantees. Most of these arrays adopted scala tympanic electrical stimulation modes based on cochlear tonotopy. In this study, electrically evoked auditory responses were analyzed to investigate differential effects of current levels in the scala tympanic electrode array. Electrically evoked compound action potential (NRT) and E-ABR responses were recorded in six cochlear implantees wearing Nucleus 24M devices in response to refer-enced and off-referenced parameter values to estimate reflection coefficients in differential stimulations. Current levels were systematically varied and channel distances were adjusted in both mono and bipolar electrode arrays. Subjective responses were also compared with these differential response data. Differential response curves were steeper at lower portions of the scale and then terminally reached saturated states in its dynamic range. Monopolar and bipolar stimulation modes showed similar patterns and these effects depended on electrode arrays and channel arrangements. This analysis may be used to objectively determine effective differential current levels and to estimate channel interactions in the scala tympanic electrode array.
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KEYWORD
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Differential level, Electrical stimulation, NRT, E-ABR
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