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June 14, 2006

Cochlear implant a speech processor

From: Jakarta Post, Indonesia - Jun 14, 2006

The skull that receives signals from a transmitter. This is worn behind the ear and looks like a hearing aid.

The speech processor is in a lightweight box about the size of a small cell phone. This can be worn around the neck or on a belt. The latest versions are in an earpiece.

Sounds are picked up by a microphone and passed to the battery-powered processor. This selects and filters the sounds and sends these as electronic signals to the transmitter. This looks like a hearing aid.

The signals go to the implant via electromagnetic induction through a magnet worn on the side of the head. This also holds the implant receiver in place. The magnet and receiver are about the size of a Rp 200 coin.

The implant includes a long, thin self-curling wire carrying an array of electrodes. The cable is wound through the cochlea, the shell-shaped organ behind the eardrum.

There are no wires connecting the internal and external devices.

The operation takes around two hours. A hole is drilled in the skull, the implant receiver fitted under the skin and the wire fed into the cochlea. Recovery in hospital usually takes one or two days. The operation is best performed on children under six. Usually only one implant is used.

The implant doesn't amplify sounds. It bypasses the outer and inner ear and stimulates the auditory nerves. The brain has to be trained to understand these signals and convert them into meaning and speech. It can take at least 18 months of therapy before a child can develop an abstract vocabulary, answer complex questions and follow conversations.

This is why total and continuous family involvement is required.

The implant doesn't need servicing and is not affected by the child's growth. A person with a cochlear implant can swim and shower but should avoid contact sports. The technology is continually being updated and the external parts can be replaced.

© 2006 The Jakarta Post.