First – outside the head there are two main elements:
1. The Behind The Ear (BTE) speech processor. This works in a similar way to a hearing aid. It has a set of microphones to pick up sounds which are then processed through a bespoke software program (called the “map”) and converted into the correct signals to send to the internal implant.
2. The Coil. This both transmits the signal from the BTE processor to the internal implant and powers the implant. It is connected to the BTE by a cable and fixes onto the head with a magnet that is attracted to a similar magnet in the implant.
Second – the internal implant:
This receives the signal from the coil and then transmits the signal down a thin cable to an electrode array that is coiled within the inner ear (cochlea) itself.
The electrode array creates lots of tiny electrical signals that directly stimulate the hearing nerve (the aural nerve) which runs from the cochlea up to the brain. This simulates the process of hearing.
More information here.