To evaluate the performance of the Nucleus 5 Cochlear Implant System.

Performance outcomes of newly implanted adult recipients using the Nucleus 5 Cochlear Implant System.

Inclusion Criteria:

• Eighteen years of age or older at the time of the study.
• Postlinguistic onset of bilateral severe-to-profound sensorineural hearing loss
• Bilateral severe-to-profound hearing loss that meets current cochlear implant criteria (<50% open-set sentence recognition in quiet scores in the ear to be implanted and <60% in the best-aided condition)
• English spoken as the primary language.
• Willingness to participate in and to comply with all requirements of the study
• Subject may receive bilateral simultaneous cochlear implants.

Exclusion Criteria:

• Previous cochlear implant experience
• Congenital hearing loss (for the purpose of this study, onset prior to 2 years-of-age).
• Ossification, absence of cochlear development or any other cochlear anomaly that might prevent complete insertion of the electrode array.
• Normal hearing in one or both ears.
• Hearing loss of neural or central origin (e.g., deafness due to lesions on the acoustic nerve or central auditory pathway).
• Active middle-ear infection.
• Unwillingness and/or inability of the candidate to comply with all investigational requirements including, but not limited to, study protocol and surgical procedure.