Cochlear Implantation in Cases of Single-Sided Deafness

Inclusion Criteria (SSD):

• Unilateral moderate-to-profound sensorineural hearing loss [Unaided residual hearing thresholds measured from 250-8000 Hertz (Hz) (Pure Tone Average (PTA) ≥70 decibel (dB) Hearing Level (HL) in the ear to be implanted]
• Normal to mild residual hearing thresholds from 250-8000 Hz in the contralateral ear (≤35 dB HL at each frequency, 250-8000 Hz)
• Greater than or equal to 18 years of age at implantation
• Duration of moderate-to-profound sensorineural hearing loss less than or equal to 5 years [Either reported by subject or documented in previous audiograms] [Can be less than or equal to 10 years if the subject consistently utilized hearing technology (such as a bone conduction device or conventional hearing aid) within the past 5 years]
• Previous experience with a current treatment option for SSD, including a conventional hearing aid, bone-conduction device, or CROS/BICROS (Bilateral Contralateral Routing Of the Signal) technology. [At least one month of listening experience with device] [Dissatisfaction with and/or discontinued use of current treatment option due to: insufficient gain, poor sound quality, and/or lack of perceived benefit]
• Aided word recognition in the ear to be implanted of 60% or less as measured with Consonant-Nucleus-Consonant (CNC) words (50-word list) [When listening with an appropriately fit hearing aid and masking applied to the contralateral ear] [Aided testing will be conducted in a sound-proof booth with the subject seated 1 meter from the sound source, facing 0° azimuth. Recorded materials will be presented at 60 dB Sound Pressure Level (SPL).] [The hearing aid output will be measured using National Acoustic Laboratory-NonLinear (NAL-NL1) targets.]
• Realistic expectations
• Willing to obtain recommended meningitis vaccinations per Center for Disease Control (CDC) recommendations
• No reported cognitive issues [Pass the Mini Mental State Examination (MMSE) screener]
• Able and willing to comply with study requirements, including travel to investigational site and study-related activities

Exclusion Criteria (SSD):

• Non-native English speaker [Speech perception materials are presented in English]
• Conductive hearing loss in either ear
• Compromised auditory nerve, including those with a history of vestibular schwannoma
• Ossification
• Inability to participate in follow-up procedures (i.e., unwillingness, geographic location)
• History of meningitis, autoimmune disease, or any medical condition that contraindicate middle or inner ear surgery or anesthesia
• Meniere's disease with intractable vertigo
• Trauma that precludes inner ear surgery
• Case of sudden sensorineural hearing loss that has not been first evaluated by a physician
• Pregnancy [Subjects who are pregnant or become pregnant prior to surgery are excluded due to the potential risk of anesthesia to an unborn child.] [Subjects who become pregnant after surgery may continue to participate in study procedures]
• Tinnitus as the primary purpose for seeking cochlear implantation
• Subject obtains a severe or catastrophic score on the Tinnitus Handicap Inventory (Newman, Jacobson & Spitzer, 1996).

Inclusion Criteria (asymmetric hearing loss):

a. Ear to be implanted i. Moderate-to-profound sensorineural hearing loss ii. PTA ≥70 dB HL iii. Aided word recognition of 60% or less as measured with CNC words (50-word list).

b. Contralateral ear i. PTA ≥35 and ≤55 dB HL ii. Aided word recognition of 80% or more as measured with CNC words (50-word list).

iii. Use of conventional amplification c. Greater than or equal to 18 years of age at implantation d. Duration of moderate-to-profound sensorineural hearing loss in the ear to be implanted is less than or equal to 5 years [Either reported by subject or documented in previous audiograms. Can be up to 10 years if the subject consistently utilized hearing technology in the ear to be implanted (such as a bone conduction device or conventional hearing aid) within the