How does a CI work?

Sound waves are picked up by a microphone and passed on to the speech processor, where they are converted into an electrical code. This is a sequence of electrical impulses similar to those used in the normal hearing process. This code is then transmitted via a coil through the skin to the implant beneath the skin.

The implant is surgically placed in the bone behind the ear. Connected to the implant body is an electrode carrier (array) carrying up to 22 electrode contacts, which are inserted into the inner ear or cochlea. These transmit the electrical impulses emitted by the implant to the auditory nerve fibres, with which they are in direct contact. Just like in the normal hearing process, the auditory nerve fibres relay these electrical impulses to the central auditory system for further processing. The central auditory system in our brain is gradually able to learn to understand and use this unfamiliar information. In this way it is possible for the brain to decode this reduced-content artificial information and utilise it to understand speech.

A cochlear implant system has two parts: the implant and the external speech processor. The implant consists of an electrode array with several electrode contacts, which is inserted into the cochlea, and the implant body. The externally worn speech processor has a microphone, which receives the sound. The signals are pre-processed in the processor and transmitted via the coil to the implant, where the electrical stimulation of the auditory nerve takes place.