The primary goal of this proposal is to test and develop a novel application of therapeutic hypothermia for veterans receiving cochlear implantation (CI) with an aim to preserve residual hearing and sensitive neural structures against surgical trauma and improve hearing outcomes post-implantation. Increasing residual hearing in veterans post-CI will likely improve their speech recognition outcomes, improve speech perception in quiet, and overall, patient benefit and usage of these devices. An increasing number of patients, that include our veterans, have some level of residual hearing at the time of implantation and can benefit from bimodal electro- acoustic devices. Surviving hair cell activity and as a result a functioning organ of Corti and neural substrate has recently been linked to speech perception outcomes. However, trauma during implantation leads to inflammation and oxidative stress that can exacerbate residual hearing loss. Successful translation of therapeutic interventions to limit pathophysiology of the injury have yet to be achieved. The present work aims to develop application(s) of localized, therapeutic hypothermia for protection of hair cells and neural substrate following CI in compromised cochleae as a result of noise and blast exposures in veterans. The specific aims are motivated by a gap in knowledge currently of the pathophysiology of CI in compromised cochleae, its relation to poor outcomes in veterans, and our preliminary data showing that localized, mild hypothermia delivered to the cochlea is effective and safe therapeutic intervention for preserving residual hearing after implantation. The results from this project can be further extended to other inner and middle ear surgeries in veterans, surgeries that also carry a risk of residual hearing loss.