This image, by Wikimedia Commons user Seslami~commonswiki, shows an implantable electronic device that allows some people to hear, or to hear better.
What we’re seeing here, according to the description there (translated from Swedish by Google), is:
The implant is placed under the skin behind the ear. The electrode wire is placed in the cochlea via the middle ear. 1. The sound processor picks up sound and converts it into a digital signal. 2. The sound processor sends the digitally encoded sound to the implant under the skin via the transmitter coil. 3. The implant receives the signal via its receiver coil, converts the digitally encoded sound, and emits signals via the electrode array. 4. The electrode wire stimulates the nerve fibers of the cochlea which send signals on to the brain which produces the hearing experience.