A cochlear implant is a surgically implanted electronic device that provides a sense of sound to a person who has profound hearing loss. A cochlear implant does not cure deafness or hearing impairment, but is a prosthetic substitute which directly stimulates the auditory nerve. Cochlear implants bypass the normal hearing process; they have a microphone and some external electronics, generally behind the ear, which transmit a signal to an array of electrodes placed within the cochlea, which stimulates the auditory nerve. As of December 2012, approximately 324,000 people worldwide had cochlear implants surgically implanted, with roughly 58,000 adults and 38,000 children in the US. There are over 12,000 in the UK.