How do Cochlear Implants Work?

Cochlear implants consist of an external part and an internal part. The external part has a microphone, battery, magnet, transmitting radio-frequency antenna and a micro-computer called a sound processor. The processor translates the surrounding sounds into signals that can be sent to the internal part of the device. The internal part is called a receiver/stimulator and includes a micro-computer, radio antenna, magnet and electrode array. The magnets are of opposite polarity and hold the external device over the internal device. The radio-frequency antennas allow digital communication between the internal and external parts.

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The Nucleus® cochlear implant system works in the following manner:

Sounds are picked up by the small, directional microphone located in the ear level processor. The speech processor filters, analyzes and digitizes the sound into coded signals. The coded signals are sent from the speech processor to the transmitting coil. The transmitting coil sends the coded signals as FM radio signals to the cochlear implant under the skin. The cochlear implant delivers the appropriate electrical energy to the array of electrodes which has been inserted into the cochlea. The electrodes along the array stimulate the remaining auditory nerve fibers in the cochlea. The resulting electrical sound information is sent through the auditory system to the brain for interpretation.

Sound is picked up by a microphone. Then the signal from the microphone is sent to the speech processor, a powerful microcomputer that filters, analyzes, and digitizes the sound signal into coded electrical signals. Next, these coded signals are sent to the transmitting coil, actually a radio frequency transmitting antenna. The transmitting coil sends the signal across the skin to the implanted receiver/stimulator (actually a radio frequency receiving antenna and another powerful micro- computer). The receiver/stimulator processes the electrical signals and sends them on to the electrode contacts that stimulate the remaining auditory nerve fibers in the cochlea. Finally the signals are carried to the brain where they are interpreted.

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