A cochlear implant is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing in both ears. These devices have been used since 2014 and have been used experimentally in some people who had acquired deafness in one ear after learning how to speak. Cochlear implants bypass the normal hearing process. They have a microphone and some electronics that reside outside the skin, generally behind the ear, which transmits a signal to an array of electrodes placed in the cochlea, which stimulate the cochlear nerve.