The Science Behind Cochlear Implants

“Sending Sound to the Brain”
Authors: J.P. Rauschecker and R.V. Shannon
Publication: Science
Date: February 8, 2002

“Sending Sound to the Brain” explores the science behind cochlear implants. I personally knew very little about how cochlear implants worked prior to reading this article, which was very science-heavy and probably intended for people with at least a basic understanding of neuroscience. However, the information in the article was informative and clearly laid out the technical details of the implants.

Profound deafness is caused by the loss of the sensory hair cells that transform sound into electrical impulses. However, people who are profoundly deaf and who still have a functioning auditory nerve can receive a cochlear implant to restore some of their hearing. A cochlear implant does not simply “hear” for the person; instead, it takes the place of the lost hair cells and turns sound into electrical impulses for the auditory nerve to send out to the brain. It serves as a sort of interpreter, turning one form of communication (sound) into another (electrical impulses), which the auditory nerve can then pass on to the brain.

The idea behind cochlear implants is fairly simple. Multiple stimulating electrodes are inserted into the cochlea of the inner ear, with electrodes situated along the basilar membrane such that a wide variety of frequencies can be accessed (the basilar membrane receives high frequencies on one end and low frequencies on the other, with a gradient in the middle). An external microphone collects sound waves, which are converted into electrical impulses by a speech processor. The electrodes use these electrical impulses to stimulate the correct auditory nerve fibers, which causes electrical signals to be sent to the brain for interpretation. All the implant is doing is taking the place of hair cells, which would normally have taken sound and converted it into electrical signals.

The article provides a clear and extremely detailed look at the science and mechanics behind cochlear implants. However, the article is extremely scientifically oriented, and thus appears to assume that, as a proven piece of technology, cochlear implants are “good” in all aspects of the word. The article boldly states that the cochlear implant has “greatly benefited many individuals with profound deafness” and that “the success of these devices is nothing short of miraculous.” There is no mention of the device’s controversy among the deaf community or of the stupendous cost of even just one cochlear implant. While understandable considering its appearance in Science, the article’s firm belief in the infallibility of science detracts from its overall purpose of providing insight into the world of cochlear implants. Even just mentioning the non-scientific aspects of the implants in a short paragraph or two would have improved the article’s overall message.