Hearing aid. Bone anchored hearing aid (BAHA) in place behind a person's ear. This system works through direct conduction of sound to the cochlea through the bone of the skull. A titanium fixture (not seen) is implanted in the skull behind the deaf ear. After three months, during which time the titanium has integrated with living bone tissue (osseointegration), the sound processor (black box) can be attached. Sound is conducted directly from the processor to the cochlea in the inner ear through the bone. This type of hearing aid is used by people with a functioning cochlea, but who lack normal sound conduction, a condition known as conductive (middle ear) hearing loss.