The goal of this investigation is to generate the needed PMCF data for the HiFocus Mid-Scala electrode. As a point of interest the investigators would like to evaluate the benefit to patients with low-frequency residual hearing implanted with the HiFocus Mid-Scala Electrode. The HiFocus Mid-Scala electrode array is designed to allow surgeons the flexibility to use a variety of contemporary surgical techniques that have been shown to enable easy insertion and to minimize cochlear trauma (see, e.g., Adunka and Buchman, 2007; Friedland and Runge-Samuelson, 2009; Roland et al., 2007). Temporal bone experiments have shown the HiFocus Mid-Scala electrode array to be straightforward to insert while causing minimal trauma to cochlear structures during and after surgery (Lenarz et al., 2010). In addition , the HiFocus Mid-Scala has already shown to be a safe electrode and promising post op clinical results in the premarketing study that is now in the final stage.

Inclusion Criteria:

• 18 years of age or older
• Definite Postlingual onset of severe-to-profound hearing loss as documented by completing main stream primary education.
• Local language proficiency
• Bilateral, sensorineural hearing loss

Exclusion Criteria:

• Previous inner ear surgery or active middle ear pathology.
• Cochlear malformation or obstruction
• 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
• Concurrent participation in other study

individuals with severe-to-profound hearing loss