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Oxford University Hospitals NHS Foundation Trust

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What is a Cochlear Implant?

A young child with a Cochlear Implant fittedCochlear Implants provide a sensation of hearing to people who have permanent, severe to profound deafness, and cannot hear the full range of speech sounds with standard hearing aids.

A Cochlear Implant is different from a hearing aid. It has two parts: one is worn like a hearing aid, behind the ear or clipped on to clothing, and the other is surgically implanted.

A Cochlear Implant turns sound into electrical signals. Instead of simply making sounds louder, like a conventional hearing aid would, the Cochlear Implant provides a sensation of hearing by directly stimulating the auditory nerve using electrical signals.

Cochlear Implant deviceHow does a Cochlear Implant work?

To understand how a Cochlear Implant works, it is useful to know about how the ear works.

With a Cochlear Implant, sound is picked up by the microphone worn on or near the ear on the external processor.

Diagram: hearing with a cochlear implant

The sounds are then processed, changed into electrical signals and passed to a transmitter coil worn on the head and kept in place via a magnet.

The signals are sent by radio waves, through the skin to the implanted receiver and down the wire to the electrode in the cochlea. When the electrode receives the signal, it makes tiny currents that travel along the auditory nerve to provide a sensation of hearing.