Place pitch versus electrode location in a realistic computational model of the implanted human cochlea.

Place pitch versus electrode location in a realistic computational model of the implanted human cochlea. Hear Res. 2014 Jun 26; Authors: Kalkman RK, Briaire JJ, Dekker DM, Frijns JH Abstract Place pitch was investigated in a computational model of the implanted human cochlea containing nerve fibres with realistic trajectories that take the variable distance between the organ of Corti and spiral ganglion into account. The model was further updated from previous studies by including fluid compartments in the modiolus and updating the electrical conductivity values of (temporal) bone and the modiolus, based on clinical data. Four different cochlear geometries are used, modelled with both lateral and perimodiolar implants, and their neural excitation patterns were examined for nerve fibres modelled with and without peripheral processes. Additionally, equations were derived from the model geometries that describe Greenwood's frequency map as a function of cochlear angle at the basilar membrane as well as at the spiral ganglion. The main findings are: (I) in the first (basal) turn of the cochlea, cochlear implant induced pitch can be predicted fairly well using the Greenwood function. (II) Beyond the first turn this pitch becomes increasingly unpredictable, greatly dependent on stimulus level, state of the cochlear neurons and the electrode's distance from the modiolus. (III) After the first turn cochlear implant induced pitch decreases as...
Source: Hearing Research - Category: Audiology Authors: Tags: Hear Res Source Type: research