The purpose of the study is to evaluate cochlear implant speech outcomes and subjective benefit for cochlear implant recipients with single-sided deafness using patient-specific, anatomy-based array selection versus standard of care with a fixed array size for all patients. Subjects will prospectively be assigned to receive an Anatomy-Based Electrode (FLEX26, FLEX28, or FLEXSOFT) or the Standard of Care Electrode array (FLEX28). Speech performance and subjective benefit will be evaluated between these two groups.

To determine the effectiveness of Anatomy-Based Electrode selection versus Standard of Care Electrode selection in SSD listeners a prospective, single-blinded study design will be used to evaluate the outcomes in these two groups by evaluating speech understanding in quiet, speech understanding in noise, subjective listening difficulty and sound quality, and datalogging.

Subjects will be randomly assigned to either group to receive an electrode based on their anatomy (ABE) or the Standard of Care electrode (SOCE). Five participants will be in each group, for a total of 10 participants.

All subjects will receive a MED-EL Cochlear Implant and will subsequently be fit with an audio processor approved by Health Canada. Post-operative evaluations will occur at one and six months post-activation.

Inclusion Criteria:

• 18 years of age or older at the time of implantation
• Unilateral severe to profound sensorineural hearing loss, as defined by a pure-tone average (500, 1000, 2000, and 4000 Hz) of 70 dB HL or greater
• Normal hearing mild hearing loss in the non-implanted ear, as defined by a pure-tone average (500, 1000, 2000, and 4000 Hz) of 40 dB or less
• Deemed an appropriate candidate by the investigator
• Fluent in English

Exclusion Criteria:

• Duration of profound hearing loss of 10 years or more
• Sudden onset of hearing loss within six months of implantation
• Evidence of non-functional cochlear nerve using appropriate imaging modality to be determined by the investigator
• 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