Hearing research
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In spite of many satisfactory results, the clinical outcome of cochlear implantation is poorly predictable and further insight into the fundamentals of electrical nerve stimulation in this complex geometry is necessary. For this purpose we developed a rotationally symmetric volume conductor model of the implanted cochlea, using the Boundary Element Method (BEM). This configuration mimics the cochlear anatomy more closely than previous, unrolled models. ⋯ The model predicts that the excitation threshold, the spatial selectivity and the dynamic range depend on the exact position of the electrode in the scala tympani. These results are in good agreement with recently published electrical ABR data. It is shown that the use of actively modelled nerve fibres is essential to obtain correct predictions for the biphasic stimuli typically used in cochlear implants and that unrolling the cochlear duct as done in previous models leads to erroneous predictions regarding modiolar stimulation.