Cochlear Implantation in Adults With Asymmetric Hearing Loss Clinical Trial

Inclusion Criteria: * 18 years of age or older * English as the native language * Have a desire for functional binaural hearing * Have failed a previous hearing aid (HA) treatment for asymmetric hearing loss (BiCROS or poor ear HA) or willing to complete a trial if necessary * Willingness to comply with all study requirements * Ability to provide informed consent * Poor ear (ear to be implanted): * Pure-tone average (PTA) at .5, 1 and 2 kilohertz (kHz) \> 70 dB HL (hereafter referred to as severe to profound hearing loss - SPHL) * Aided word recognition score (CNC Word Test) at 60 dB SPL ≤ 30% * Duration of SPHL ≥ 6 months * Onset of hearing loss ≥ 6 years of age * Better ear: * PTA at .5, 1, 2, 4 kHz of 40 to 70 dB HL * Currently using a HA * Aided word recognition score (CNC Word Test) at 60 dB SPL \> 40% * Stable hearing for the previous 1-year period. "Stable" is defined as thresholds that have not changed by more than 10 dB at 2 or more octave interval audiometric frequencies Exclusion Criteria: * Medical condition that contraindicates surgery * Actively using an implantable device in the ear to be implanted * Known cochlear malformation or obstruction that would preclude full insertion of the electrode array in the ear to be implanted * Hearing loss of neural or central origin * Unrealistic expectations related to the benefits and limitations of cochlear implantation * Unwillingness or inability to comply with all investigational requirements