Mechanical stimulation of cochlea for treatment of hearing loss: Comparison between forward stimulation and reverse...

Reverse stimulation is a stimulation mode of the active middle-ear implants (AMEIs), targeted at moderate conductive hearing loss and mixed hearing loss. However, previous studies investigated reverse stimulation through passive cochlear models that simulate profound sensorineural hearing loss, which is beyond the AMEI's indications. Therefore, we investigated the cochlear responses to reverse stimulation under different hearing loss and compared them with those to forward stimulation.

The human ear model consists of a human ear macro dynamic model, a cochlear micro dynamic model, and a cochlear circuit model. The human ear macro dynamic model and cochlear micro dynamic model were developed by simplifying the human ear tissues into stiffness, damping, and mass. The cochlear active amplification was realized by coupling the cochlear circuit model. Based on the model, the cochlear responses to forward and reverse stimulation were calculated.

The results show that the cochlear responses to reverse stimulation are higher than those to forward stimulation, and the difference in cochlear responses decreases and then increases with increasing stimulus magnitude. Conductive hearing loss significantly reduces cochlear response to forward stimulation but has less effect on reverse stimulation. Outer hair cell hearing loss significantly reduces cochlear response to both forward and reverse stimulation, but the effect diminishes to nothing as the stimulation amplitude increases.

This study compared the cochlear responses differences in normal hearing and hearing loss to forward and reverse stimulation, contributing to the optimization of the round window stimulating AMEIs.