Safety and Efficacy of a Drug Eluting Slim Modiolar Electrode Array

Inclusion Criteria:

• 18 years or older, at time of consent.

• Postlinguistic moderately severe to profound sensorineural hearing loss, defined bya four frequency (500, 1000, 2000, 4000 Hz) pure-tone average unaided threshold (PTA4) ≥ 60 decibels hearing level (dB HL), in the ear to be implanted (For thisstudy, moderately severe is defined by a four-frequency, pure-tone average threshold (PTA4) over the range 500 through 4000 Hz of more than 55 dB HL through 70 dB HL,inclusive. Profound is defined by a PTA4 of more than 90 dB HL).

• Pure-tone average unaided threshold (500 through 4000 Hz) ≥ 30 dB HL, in thecontralateral ear.

• Preoperative aided word score ≤ 40% correct in the ear to be implanted.

• Evidence of pneumococcal vaccination (e.g., Pneumovax) according to localguidelines.

• Candidate is proficient in the language used to assess speech perceptionperformance.

• Willing and able to provide written informed consent.

Exclusion Criteria:

• Intra-axial (within the brain) lesions or deafness due to lesions of the acousticnerve affecting the ear to be implanted.

• Middle ear infection (including acute otitis media, chronic otitis media,suppurative otitis media, or serous drainage) in the ear to be implanted either atthe time of surgery or within 3 months prior to enrolment.

• Active autoimmune disease or active immunosuppressive therapy.

• Presence of a tympanic membrane perforation or a history of otologic surgery within 3 months prior to enrolment, in the ear to be implanted.

• Previously reported diagnosis of auditory neuropathy, in the ear to be implanted.

• Previously reported diagnosis, in the ear to be implanted, of Large VestibularAqueduct Syndrome (LVAS), Meniere's disease, or cochlear hydrops.

• Ossification, otosclerosis, malformation or any other cochlear anomaly, such ascommon cavity, that might prevent complete insertion of the electrode array, in theear to be implanted.

• Current cerebrospinal fluid (CSF) shunts or drains, existing perilymph fistula,skull fracture or CSF leaks.

• Previously reported diagnosis of bacterial meningitis.

• Known allergic reaction or contraindication to dexamethasone or corticosteroids.

• Severe, or poorer, bilateral sensorineural hearing loss prior to 5 years of age, asreported by the subject. (For this study, severe is defined by a PTA4 of more than 70 dB HL through 90 dB HL, inclusive).

• Severe, or poorer, sensorineural hearing loss for more than 20 years, as reported bythe subject, in the ear to be implanted.

• Prior cochlear implantation in either ear.

• Medical plan for cochlear implantation during the clinical investigation,contralateral to the ear to be implanted.

• Medical or psychological conditions that contraindicate general anaesthesia,surgery, or participation in the clinical investigation as determined by theInvestigator.

• Unrealistic expectations on the part of the subject regarding the possible benefits,risks, and limitations inherent to the surgical procedure(s) and prosthetic devices,as determined by the Investigator.

• Women who are pregnant.

• Additional disabilities that may affect the subject's participation or safety duringthe clinical investigation.

• Unable or unwilling to comply with all the requirements of the clinicalinvestigation as determined by the investigator.

• Investigator site personnel directly affiliated with this study and/or theirimmediate families. Immediate family is defined as spouse, parent, child, orsibling.

• Cochlear employees or employees of Contract Research Organisations or contractorsengaged by Cochlear for the purposes of this investigation.

• Current participation, or participation in another interventional clinicalstudy/trial in the past 30 days, involving an investigational drug or device unlessCochlear sponsored and determined by Investigator or Sponsor to not impact thisinvestigation.