A cochlear implant is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf. It works by directly stimulating the auditory (hearing) nerves with electrical impulses.
American William House (b. 1923) is credited with being the first surgeon to implant a cochlear-type device. In 1957 House saw an article by two French surgeons who had inserted an electrode into the auditory nerve of a deaf man and shown that he could perceive sounds when the nerve was stimulated. In 1961 House placed cochlear implants in three patients, who gained some benefits. After research into the best positioning of the electrodes, House created the first wearable implant in 1969.
Despite hostile criticism and fears that electrical stimulation of the cochlea might destroy brain tissue or spread infections, by December 1984 cochlear implants had the U.S. Food and Drug Administration stamp of approval, and were no longer deemed experimental. In the device, sound is picked up by a microphone worn near the ear and transmitted to a speech processor worn on the body. The sound is then analyzed and converted into electrical signals that are transmitted to a surgically implanted receiver behind the ear. The receiver sends the signal through an electrode array (wire) into the inner ear, where the electrical impulses are transmitted to the brain.
Throughout the 1990s further improvements were made, particularly the miniaturization of speech processors that could be incorporated into hearing- aid-like devices. Finally, in 2005 the first fully implantable devices were developed.
