A cochlear implant (CI) is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. The cochlear implant is often referred to as a bionic ear. Unlike hearing aids, the cochlear implant does not amplify sound, but works by directly stimulating any functioning auditory nerves inside the cochleawith an electric field. External components of the cochlear implant include a microphone, speech processor and an RF transducer or primary headpiece coil. A secondary coil is implanted beneath the skull's skin and inductively coupled to the primary headpiece coil. The headpiece coil has a magnet by which it attaches to another magnet placed on the secondary coil often beside the cochlear implant. The implant relays the incoming signal to the implantedelectrodes in the cochlea. The speech processor allows an individual to adjust the sensitivity of the device. The implant gives recipients additional auditory information, which may include sound discrimination fine enough to understand speech in quiet environments. Post-implantation rehabilitative therapy is often critical to ensuring successful outcomes.
As of 2009, approximately 150,000 people worldwide had received cochlear implants; in the United States, about 30,000 adults and over 30,000 children are recipients. The vast majority are in developed countries due to the high cost of the device, surgery and post-implantation therapy. A small but growing segment of recipients have bilateral implants (one implant in each cochlea).
There is disagreement whether providing cochlear implants to children is ethically justifiable, renewing a century-old debate about models of deafness that often pits hearing parents of deaf children against the Deaf community.