A Study to Explore Improved Features and a Simplified Treatment Approach for a Totally Implantable Cochlear Implant (TICI) Research System in Adults With Severe Hearing Loss

Inclusion Criteria: * Aged 18 years or older, at time of consent * Candidate for cochlear implantation as assessed by the implanting clinic * Fluent in English, as determined by the investigator * Willing to participate in and comply with all requirements of the protocol * Willing and able to provide written informed consent Exclusion Criteria: * Severe, or poorer, bilateral sensorineural hearing loss prior to five years of age, as reported by the subject * Duration of severe to profound hearing loss greater than 20 years in the ear to be implanted as reported by the subject or by audiometric history, if available * Ossification, otosclerosis, malformation or any other cochlear anomaly, such as common cavity, that might prevent complete insertion of the electrode array * Deafness due to lesions of the acoustic nerve affecting the ear to be implanted * Medical or psychological conditions that would contraindicate undergoing anaesthesia, surgery or participation in the clinical investigation, as determined by the investigator * Additional disabilities that may affect the subject's participation or safety during the clinical investigation, as determined by the investigator * Unrealistic expectations on the part of the subject regarding the possible benefits, risks and limitations that are inherent to the surgical procedure and prosthetic device, as determined by the investigator * Desire to use an integrated acoustic component post-implantation * Unable or unwilling to comply with the requirements of the clinical investigation as determined by the Investigator * Investigator site personnel directly affiliated with this study and/or their immediate families; immediate family is defined as a spouse, parent, child, or sibling * Cochlear employees or employees of Contract Research Organizations or contractors engaged by Cochlear for the purposes of this investigation. * Current participation, or participation in another interventional clinical study/trial in the past 30 days, involving an investigational drug or device (unless Cochlear sponsored and determined by investigator or Sponsor to not impact this investigation)