Cochlear Implants

A cochlear implant is a surgically implanted or placed device that helps a person with bilateral severe to profound hearing loss with intact hearing nerve (also called auditory nerve or 8th cranial nerve) hear near-normal sounds again. The cochlea is a small snail-shaped part of the inner ear. It turns sound vibrations into electrical signals that travel along the auditory nerve. The brain translates these signals into recognizable sounds. Note that cochlear implants are different from hearing aids. A hearing aid makes sounds louder so people with hearing loss can hear. Cochlear implants bypass damaged parts of the cochlea to stimulate the auditory nerve directly. They may help when patients do not get any benefit from the conventional hearing aids.

How Do Cochlear Implants Work?

Cochlear implants have two components (external component and internal component):

  • External component consists of a microphone and speech processor that sits outside the body. The microphone picks up sound and sends it to the processor. The processor is a minicomputer that changes the sound into digital information. Then, a transmitter sends the digital signal to the receiver/stimulator. 


  • Internal component consists of a receiver/stimulator that’s placed under skin and muscle behind the ear. This gets information from the processor. It sends electrical impulses by a thin wire to electrodes placed in the cochlea. The electrodes stimulate the auditory nerve directly. The message goes to the brain (auditory cortex) and the brain can use the information to recognize sounds and understand speech.



Is Hearing With a Cochlear Implant Like Normal Hearing?

Sound quality from a cochlear implant is different from that in normal hearing. That’s because a limited number of electrodes take over the work of the thousands of hair cells in a normal cochlea. The sounds coming through a cochlear implant won’t be totally “natural.”

But cochlear implants let someone sense sound that they couldn’t hear otherwise. Infants who have never heard sounds before, soon will build new brain pathways to start to make sense of these sounds. With therapy, auditory training and practice, all cochlear implant users can learn how to interpret these sounds to better understand speech.

Who Can Get a Cochlear Implant?

Audiologists consider cochlear implants for children under 12 months of age with profound hearing loss in both ears. Older children with serious hearing loss also may get cochlear implants. A cochlear implant team will help decide if cochlear implants are a good option. This team includes an audiologist (hearing) doctor, an ear-nose-throat (ENT) doctor, a speech therapist, a psychologist, and a social worker.

Children being considered for cochlear implant surgery will:

  • Get a complete hearing assessment done
  • Have speech/language evaluations done
  • Get checked to see if they have acquired hearing loss (post lingual deafness)
  • Use a hearing aid for a while to see if it helps them in anyway
  • Get computed tomography (CT) or magnetic resonance imaging (MRI) scans to look at the inner ear and the bones that surround it.

Children might not qualify for the implants if:

  • Their residual hearing is “too good” (they can hear some sound or speech and get any benefit at all from the hearing aids).
  • Their hearing loss isn’t due to a problem with the cochlea.
  • Their cochlea is anatomically deformed.
  • They’ve been profoundly deaf for a long time and have no speech and language.
  • The auditory nerve is damaged or absent.