The purpose of the study is to evaluate the long-term safety and effectiveness of cochlear implantation of the approved population in adults and children with single-sided deafness and asymmetric hearing loss.

The study will be conducted as a single-subject, repeated measures, multi center study at 6 sites. Sixty-five subjects will be enrolled in this study. Six centers across the United States and Canada will recruit subjects into this study. Study subjects will be followed for a minimum of 3 years post-implantation of the device.

Inclusion Criteria:

• Five years of age or older at the time of implantation
• Unilateral profound hearing loss, as defined by a pure-tone average (500, 1000, 2000, and 4000 Hz) of 90 dB or greater in the ear to be implanted
• Sensorineural hearing loss in the ear to be implanted, as defined by an air-bone gap less than or equal to 10 dB at two or more frequencies out of 500, 1000, 2000, and 4000 Hz and a diagnosed pathology of the outer or middle ear
• Normal hearing or mild to moderate hearing loss in the non-implanted ear, as defined by a pure-tone average (500, 1000, 2000, and 4000 Hz) of 55 dB or less
• Word recognition in the ear to be implanted of 5% or less on CNC word score in quiet
• Previous experience with an appropriately-fit Contralateral Routing of Signal (CROS) hearing aid, BI-Contralateral Routing of Signal (CROS) hearing aid, bone conduction, or traditional hearing aid, as deemed appropriate by investigator
• Fluent in English

Exclusion Criteria:

• Duration of profound hearing loss of 10 years or more
• Absence of cochlear development or non-functionality of cochlear nerve
• Other retrocochlear hearing loss
• Evidence of severe cochlear malformation (i.e., common cavity or ossification)
• External or middle ear infection
• Suspected developmental or cognitive concern
• Other medical contraindication for surgery or anesthesia