Interventions: description
The standard surgical procedures for cochlear implantation will be followed. A retroauricular S-shaped incision will be made to expose the mastoid. The electrode array will be inserted via a posterior tympanotomy and round window implantation by soft-surgery techniques. The R/S device will be fixated according to the group the patient is allocated to. The bony recess technique will be used in group A; a bony recess will be drilled at an angle of 30 to 60° relative from the Frankfurt Horizontal plane. The provided silicone dummy will be used to ensure the depth and dimensions of the recess are sufficient. No tie-down sutures will be used. Patients allocated to group B will be operated using the subperiosteal tight pocket technique as described by Balkany et al. [