Cochlear implants are a successful treatment for severe hearing loss in both children and adults. The procedure involves placing an electrode array into the cochlea to stimulate the auditory nerve, helping patients to hear. For the best results, it's crucial to place the electrode precisely and gently to avoid damaging delicate structures inside the ear. However, currently, surgeons lack feedback on the insertion status, making it difficult to confirm correct electrode positioning, especially regarding insertion depth, such as angle, frequency, or millimeters. New technologies are being developed to provide feedback during surgery, helping surgeons place the electrode more accurately. One such technology, recently developed by MED-EL, is called OTOGUIDE. This software offers immediate information on the electrode's position and functioning during the operation, aiming to improve surgical precision and hearing outcomes.

This clinical investigation aims to evaluate the performance and safety of OTOGUIDE, which assists surgeons during cochlear implant procedures by helping identify the position and angle of electrode contacts placed inside the cochlea. The primary objective is to confirm that OTOGUIDE can accurately detect which electrodes are inserted into the cochlea, with results that are more than 80% consistent with standard CT imaging (either during or after surgery). The secondary objective is to verify that OTOGUIDE can estimate the insertion angle of a specific electrode (C1) with a margin of error smaller than 60 degrees compared to CT imaging.

Participants who agree to take part and sign the informed consent form will undergo up to three study visit, which coincides with their scheduled routine cochlear implant surgery visits. During the Surgery Visit intraoperative measurements will be performed using both OTOGUIDE and the MAESTRO system. CT imaging (either during or after surgery, depending on routine clinical practice) will be used to verify the electrode array's position inside the cochlea.

Inclusion Criteria:

• Minimum age of eighteen (18) years at time of enrolment.
• Subjects to be implanted with a compatible MED-EL cochlear implant (CI) (Mi1200 SYNCHRONY (PIN), Mi1210 SYNCHRONY ST, Mi1250 SYNCHRONY 2 (PIN), Mi1260 SONATA 2) according to clinical routine.
• Signed and dated informed consent before the start of any study-specific procedure.

Exclusion Criteria:

• Previously having received a CI on the ear to be tested (Re-implantation).
• Evidence of ossification or any other cochlear anomaly (e.g., malformation) that might prevent complete insertion of the electrode array or might cause increased risk of infection (e.g. dysplastic cochlear), as confirmed by medical examination and/or as per CT/MRI.
• Known absence of cochlear development or if the cause of deafness is non-functionality of the auditory nerve and/or the upper auditory pathway.
• Evidence of active external or middle ear infection or history of recurrent middle ear infection in the ear to be implanted.
• Acute cholesteatoma
• The tympanic membrane is perforated in the ear to be implanted.
• Pre-existing condition known to prohibit CT imaging before and after cochlear implantation.
• Women being pregnant or nursing.
• Anything that, in the opinion of the Investigator, would place the subject at increased risk or preclude the subject's full compliance with or completion of the study.