Mechanical Effects of Cochlear Implant on Acoustic Hearing

Residual hearing loss in cochlear implant users is investigated using the mechanical-human-cochlear model. Hearing loss due to stiffening of the round window increases significantly as input frequencies decrease from 3 kHz to 1 kHz but remains constant at lower frequencies, while loss due to the presence of an electrode insert becomes significantly higher at lower frequencies (<1 kHz). The latter also shifts the characteristic frequency map towards the basal end of the cochlea. In the region away from the end of the electrode insert, cochlear function recovers, but the user still suffers from hearing loss caused by round window stiffening.