Cochlear implant devices

A cochlear implant (CI) is an electronic device which may be suitable for children and adults who do not get enough benefit from conventional hearing aids. Hearing aids work by making sounds louder. A CI is different. Sounds are turned into tiny electrical pulses and sent directly to the nerve endings in the inner ear.
A CI consists of two parts: an inside part (implanted during an operation) and an outside part which is worn behind the ear, on the side of the head or on the body. Both parts work together.

The inside part (under the skin)

The inside part is made up of the receiver/stimulator package (with an internal magnet) and the electrode array. An operation is needed to put the implant in. The receiver/stimulator package lies under the skin behind the ear, and can be felt if touched gently. It is connected to the electrode array which is inserted into the cochlea in the inner ear.
The receiver/ stimulator package picks up the radio signal from the outside transmitter coil. Tiny pulses of electricity are sent to the electrodes in the cochlea. Different electrodes each take a part of the signal, so that different sounds can stimulate different areas in the cochlea. The signal from the electrodes activates the nerve of hearing, which then takes the message along the usual pathway to the brain. The brain then understands this as sound.

The outside part

The outside part is the sound processor and transmitter coil. Some sound processors combine the processor and coil into a single unit. The processor powers and activates the inside part, and the patient can only hear sound when it is worn and switched on.
A microphone on the sound processor picks up sounds and changes them into electrical signals. The signal passes through the skin using radio waves to meet the inside parts of the implant.
The processor will be carefully set by an Audiologist to make the signal just right. The batteries usually need to be recharged daily.