This is a prospective study designed to evaluate the safety and performance of the HiRes Ultra Cl HiFocus MS Electrode and HiRes Ultra 3D Cl HiFocus MS Electrode (Ultra X) under normal conditions of use as it is approved for this device.

This study is set up to document any adverse events and comparing pre- to post-implant benefit to subjects. Any adverse events associated with the device will be documented via Advanced Bionics complaint handling system for the lifetime of the device. A within-subjects repeated-measures design will be employed. Speech perception will be evaluated preoperatively with conventional amplification to determine candidacy and to establish baseline performance. Efficacy parameters are speech perception data which will be collected according to clinical routine with a 6 month follow up period. Subjects will be implanted unilaterally with the Ultra X according to standard clinical care.

The primary efficacy objective is to demonstrate that mean monosyllabic word recognition score with the Ultra X used in combination with a sound processor programmed with the latest fitting software six months after activation is at least 20% better than the mean word score at baseline with conventional amplification in the same ear.

The primary efficacy endpoint is reached six months after device activation.

Inclusion Criteria:

• No previous experience with any auditory implant
• 18 years of age or older
• Postlingual onset of severe hearing loss (≥ 4 years of age)
• Limited benefit from appropriately fitted hearing aids, defined as scoring 60% or less in Freiburger Monosyllabic word test
• German language proficiency
• Willingness to participate in all scheduled procedures outlined in the protocol

Exclusion Criteria:

• 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
• Pregnancy at time of surgery.

30 adult subjects with valid and useable data

Adverse event were collected from the inclusion until six months after device activation