Inclusion Criteria:  uni- or bilaterally deafened and deaf patients with cochlear implants (one- or two- sided) from Advanced Bionics (AB), model HiRes 90K and newer majority given informed consent legally competent and mentally able to follow the instructions of the personnel  Exclusion Criteria:  unsuccessful CI implantation (device or electrode defects, incomplete electrode array insertion, missing neuronal stimulus responses) pregnant and/or breastfeeding women severe pre- or concomitant disease or reduced general ground condition, so that an outpatient presentation in the ENT polyclinic is not possible life expectancy of less than six months the patient has received a study medication within the last 30 days within the framework of another study simultaneous participation in another clinical intervention study anticipated lack of compliance alcohol or drug abuse the patient is placed in an institution by order of the authorities or court patients who are in a dependent or employed relationship with the sponsor, investigator, or their deputy