04 December 2009

What a Cochlear Implant Does?

The cochlear implant artificially stimulates the inner ear area with electrical signals, sends those signals to the hearing nerve, and allows the user to hear. Although sound quality is sometimes described as "mechanical" and not completely like that experienced by a person with normal hearing, the cochlear implant provides users with the ability to sense sound that they couldn't hear otherwise. Improvements in the way the implant processes sound information are continuously being made to make the sound seem more natural.

The actual cochlear implant consists of an implant package, which is secured inside the skull, and a sound and speech processor, which is worn externally (outside the body). Several components of the cochlear implant work together to receive sound, transfer it to the hearing nerve, and send it to the brain.

The implant package is made up of:

  • a receiver-stimulator that contains all of the electronic circuits that control the flow of electrical pulses into the ear
  • an antenna that receives the signals from the external sound and speech processor
  • a magnet that holds the external sound and speech processor in place
  • one wire containing electrodes that are inserted into the cochlea (the number of electrodes can vary depending on the cochlear implant model type used). The electrodes act much like normal functioning hair cells and provide electrical charges to stimulate the hearing nerve.

The sound and speech processor is a minicomputer that processes sound into digital information, and then sends that information to the implant package in the form of electrical signals. The sound and speech processor is worn externally and looks a lot like a normal hearing aid. Depending on the type of sound and speech processor used, it can either be worn as a headset behind the ear or in a belt, harness, or pocket.

The components of the sound and speech processor include:

  • the actual sound and speech processing device (which can either be a body-level model that can be clipped onto clothing like a portable radio, or an ear-level model that's hooked over the ear)
  • a microphone
  • a transmitter that sends the signals to the implant package. The transmitter also includes a magnet that helps the user align the processor with the implant package.

For the cochlear implant to work, the implant package and the sound and speech processor must be aligned — that's what the magnets are for. By lining up the magnets, both the implant package and sound and speech processor are secured and work as one device.

When the implant package and the sound and speech processor aren't completely aligned, the device doesn't work and the person can't hear. Because both components need to be aligned for the user to hear, some people take the sound and speech processor off at night to sleep soundly. Others leave it on all the time.

From: http://kidshealth.org

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