The purpose of this study is to determine the feasibility of preserving low-frequency acoustic hearing in adults with a moderate degree of hearing loss in the low frequencies and severe-to-profound hearing loss in the mid-to-high frequencies who are implanted with the HiRes™ 90K Advantage implant with HiFocus™ Mid-Scala electrode.

Inclusion Criteria:

• No previous cochlear implant experience
• 18 years of age or older
• Up to a moderate sensorineural hearing loss in the low-to-mid frequencies (pure tone average ≤ 65 dB HL for 125, 250, 500, and 1000 Hz) and a severe-to-profound sensorineural hearing loss in the high frequencies (pure tone average ≥ 70 dB HL for 2,000, 4,000, and 8,000 Hz) in the ear to be implanted
• Aided monosyllabic word score of 10-50% in the ear to be implanted
• Up to a moderate sensorineural hearing loss in the low-to-mid frequencies (pure tone average ≤ 65 dB HL for 125, 250, 500, and 1000 Hz) and a severe-to-profound sensorineural hearing loss in the high frequencies (pure tone average ≥ 70 dB HL for 2,000, 4,000, and 8,000 Hz) in the contralateral (non-implanted) ear
• English language proficiency
• Willingness to participate in all scheduled procedures outlined in the protocol

Exclusion Criteria:

• Previous inner ear surgery
• Cochlear malformation or obstruction that would preclude full 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 the study-related procedures
• Evidence of central auditory lesion or compromised auditory nerve