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How a Cochlear Implant Works

The cochlear implant bypasses the damaged parts of the inner ear and directly stimulates the remaining hearing nerve fibers in the cochlea with electrical signals.
The cochlear implant consists of two basic components: an outer (external) and an inner (internal) device. The external device consists of a speech processor (see #2, figure below) (worn either as a behind-the-ear device(#2) or a single circular disc behind the ear), a transmitting coil(#4), a directional microphone(#1) and connecting cords(#3). The internal device consists of a receiver/stimular(#5) (placed directly below the skin) and a multi-electrode wire array(#6), which is inserted into the inner ear (cochlea). The transmitting coil of the external device is secured over the receiver/stimulator of the internal device through magnetic attraction.

The Cochlear Implant System works in the following manner:

  • Sounds are picked up in the small, directional microphone located in the ear level speech processor.
  • The speech processor filters, analyzes and then digitizes sound into coded electrical 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 signals to the electrode array, which has been inserted into the cochlea.
  • The electrodes along the array stimulate the auditory nerve (hearing nerve) fibers in the cochlea.
  • The resulting electrical signal is sent through the auditory system to the brain where the signal is interpreted. After a period of rehabilitation, these signals are interpreted in the brain as sound.

Types of Cochlear Implants

The Ear Institute of Chicago offers cochlear implants from three different manufacturers. These implants include devices made by Cochlear CorporationAdvanced Bionics Corporation, and the MED-EL Corporation. Each device is approved by the Food and Drug Administration (FDA). The patient is allowed to choose the implant they desire. For more information regarding each device, please see our “comparison of cochlear implants” page.

The Ear Institute of Chicago also offers hybrid cochlear implant systems. A hybrid cochlear implant system is considered when a patient has significant low-frequency hearing. A hybrid system consists of combined acoustic and electrical hearing.
The hybrid speech processor combines acoustic amplification for the low frequencies with electric stimulation for the high frequencies. For patients that qualify for this option, a special hybrid electrode array may be considered or the standard electrode array may be used with an atraumatic surgical technique. The implant type will be decided by the physician depending on the degree of hearing loss.

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"Who is a Candidate for a Cochlear Implant".