Inclusion Criteria:

- 18 years of age or older

- English as the primary language

- Medically and psychologically suitable

- Willing to receive/have received meningitis / pneumoccal vaccinations

- Able to comply with study requirements, including travel to the investigational site

- Cochlear or retrocochlear anomaly/pathology that interferes with transmission of
auditory information from the cochleae to the brainstem, resulting in severe to
profound bilateral deafness (thresholds of 90 dB or worse in both ears on pure tone
audiometry ranging from 250 to 2,000 Hz and speech recognition scores ≤ 30% in both
ears). All subjects will undergo bone conduction audiometry and tympanometry to
confirm sensorineural hearing loss and rule out potential middle ear disorders.

- Conditions that cannot be otherwise treated, with conventional hearing aids or
cochlear implants. If CI were previously used, subjects will have had a failed
response, defined as ≤ 30% speech recognition and patient perception of
inadequate benefit to continue using the device.

- Expected subjects include those with these diagnoses:

- Bilaterally severe/completely ossified cochleae

- Bilateral cochlear malformations leading to poor CI outcomes

- Bilateral temporal bone fractures, where the VIIIth cranial nerves have
been disrupted

- Bilateral cochlear nerve agenesis

- Not a CI candidate based on above listed pathology, intolerable adverse
effects with CI (e.g. stimulation of the facial nerve), or Evoked Auditory
Potential testing predictive of a poor response

Exclusion Criteria:

- Anomalies/pathology involving the brainstem or cortex

- Retrocochlear pathology resulting from NF2 or other types of cranial nerve or
brainstem neoplasm

- Co-existing medical conditions that require irradiation of the brainstem or auditory
cortex

- Medical or psychological conditions that serve as contraindication to surgery

- Additional handicaps that would prevent or limit participation in evaluations

- Unrealistic patient or family expectations regarding the benefits, risks, and
limitations inherent to the procedure and the prosthetic device

- Pregnant women