NICE guidance

What is a cochlear implant?

An implant consists of two distinct parts, the internal device or cochlear implant itself, and the external part or speech processor, which is made up of the processor (shaped like a hearing aid) and a transmitter coil.

The cochlear implant consists of an electronic receiver-stimulator package, which sits in a shallow bed drilled out of the mastoid bone, together with an electrode array which is fed into the cochlea itself.

The speech processor sits on the ear like a conventional hearing aid. The coil is held in place over the implanted receiver by means of a magnet, so there are no plugs or connections through the skin.

Sound enters the microphone of the speech processor and is processed into an electrical signal, which is transmitted through the skin to the implanted receiver. This signal is then sent as a stream of tiny electrical pulses to the electrode in the cochlea, where they pass directly to the auditory nerve, providing a sensation of hearing. The patient is only able to hear sound if the external speech processor is worn and is switched on.

By Tracey Twomey
Clinical Scientist in Audiology and Manager of the Nottingham Cochlear Implant Programme

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