Thanks to recent improvements in the cochlear implant (CI) surgical technique and the electrode design, it is now often possible to preserve residual acoustic hearing in the low frequencies during the insertion of a CI in the same ear. CI users with preserved low frequency hearing receive combined electric-acoustic stimulation (EAS) and show improved speech performance scores especially in noisy situations when compared to CI users without preserved residual hearing.
However, it has been shown that simultaneous acoustic and electric stimulation causes interactions between both modalities. One form of such interaction is masking. Masking between electric and acoustic stimulation has been observed in auditory nerve fiber (ANF) spike trains in animals as well as in electrocochleographic (ECochG) responses and psychophysical experiments in humans (see Project EAS-Masking). To date, it remains unclear at which stage of the auditory pathway these masking effects arise (i.e. at the level of hair cells, the auditory nerve, or more centrally).
In this project, we develop a computational model of the acoustically and electrically stimulated auditory nerve to better understand the underlying interaction mechanisms in EAS users. Existing models simulate ANF spiking for sole acoustic or electric stimulation. Our idea is to couple a model of acoustically evoked spiking activity with a model of electrically induced spikes to simulate the electric-acoustically stimulated auditory nerve. Our current implementation shows appropriate spiking responses to both acoustic stimulations of remaining hair cells and electric stimulation of the ANF, as well as inhibitory interaction between both modalities.
This project is funded by the German Research Foundation (Deutsche Forschungsgemeinschaft (DFG)) - Project number: 396932747
|Head of Research Group:
||[Prof. Dr.-Ing. Waldo Nogueira]|
||DHZ-Deutsches HörZentrum Hannover
|Phone:||+49 (0)511 532 8025|
|Fax:||+49 (0)511 532 6833|
- A computational model of a single auditory nerve fiber for electric-acoustic stimulation D. Kipping, W. Nogueira (Under Review). Submitted to the Journal of the Association for Research in Otolaryngology (JARO) in 9/2021.