Evaluation of the safety and efficacy of the HiFocus V electrode array in adults with severe-to-profound hearing loss through analysis of post-implant benefits of the HarmonyTM HiResolutionTM Bionic Ear cochlear implant system

* * 18 years of age
* Postlingual onset of severe-to-profound hearing loss (* 4 years of age)
* Sensorineural hearing loss of severe or greater degree in both ears, defined as a pure-tone average (PTA: 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz) of * 70 dB HL
* Marginal hearing aid benefit with appropriately fitted hearing aids, defined as a monosyllabic word score in quiet of * 50% in the best-aided condition
* Proficient in the local language of the investigational center
* Willingness to participate in all scheduled procedures outlined in the protocol

* Cochlear malformation or obstruction that would preclude adequate insertion of electrode array
* Presence of additional disabilities that would prevent or interfere with participation in the required study procedures
* Medical or psychological conditions that contraindicate surgery or impact the ability to manage an implanted device or to participate in the study related procedures
* Evidence of central auditory lesion or compromised auditory nerve
* Pregnancy at time of surgery (responsibility of the hospital)