Esteem Totally Implantable Hearing System

Inclusion Criteria: * Subject is 18 years old * Subject understands the nature of the procedure and has signed the Subject Informed Consent Form prior to the procedure * Subject is willing and able to comply with specified follow-up evaluations and understands the audiological test procedures and use of the Esteem System. * Subject has mild to severe sensorineural hearing loss between 500 and 4000 Hz in the ear to be implanted with pure tone air-conduction threshold levels within the limits of a Hearing Aid (HA) as follow: Freq (Hz) 500 1000 2000 3000 4000 LL\* (dB HL) 30 35 35 35 35 UL\* (dB HL) 100 100 100 100 100 \*LL = Lower Level; UL = Upper Level * Subject's air-bone gap is no greater than 10 dB at 4 of the 5 following frequencies: 500, 1000, 2000, 3000 and 4000 Hz. * Subject has an unaided maximum word recognition score of greater than or equal to 60% with recorded delivery using a phonetically balanced word list at SRT + 40 dB or at maximum tolerable presentation level. * Subject is a current user of a properly functioning and appropriately fit hearing aid. This is defined as the subject has used this aid for at least four (4) hours (average) per day (in the ear to be implanted) for at least three (3) months for a new aid or one (1) month for an adjusted aid. * Subject's hearing aid, in the ear to be implanted, shall appropriately fit optimally. * Subject has normally functioning eustachian tube * Subject has normal tympanic membrane * Subject has a normal middle …