University of Iowa Health Science Relations and
Jay Rubinstein, MD, MS, PhD
Associate Professor of Otolaryngology-Head & Neck Surgery/Biomedical Engineering
First Published: November 2000
Last Revised: March 2004
Peer Review Status: Internally Peer Reviewed

Lip-reading and sign language have previously been the most effective methods of communication for people who are deaf and for whom hearing aids are not effective. Yet, some people with nerve deafness can gain a sense of sound, thanks to cochlear implants.

Cochlear implants are devices that are surgically placed in the inner ear. Normally, the bones of the middle ear transmit sound to the inner ear, cells translate the vibrations into electrical currents, which are then interpreted by the brain. With nerve deafness, these cells are lost. Cochlear implants stimulate the auditory nerve directly, creating electrical impulses.

"It's not normal hearing, but it is a sense of sound," says Dr. Jay Rubinstein, associate professor of otolaryngology and biomedical engineering at the University of Iowa College of Medicine and staff physician at the UI Hospitals and Clinics. "The quality of the sound might depend on how many properly functioning cells are left."

The implant is placed in the cochlea and connected to the auditory nerve with thin wires. The patient wears an outer hearing aid with a microphone that is connected to a speech processor worn on a belt or on the ear. The microphone transmits sound to the implant, which converts it to electrical impulses that travel the thin wires and stimulate the auditory nerve.

The implants work well for adults who have lost their hearing later in life, after they have already learned, and heard, language, Rubinstein says. "For people who have no representation of spoken language in their brain, it is difficult to understand sounds. For someone who knows language, the sounds make more sense."

However, research has shown that the implants also are useful for children who have suffered hearing loss before they have learned to speak. By using cochlear implants some children may actually learn to speak. A recent UI study of 54 children with cochlear implants indicates that most of the children have some speech recognition and can comprehend sounds independent of visual images.

While the quality of sound differs from patient to patient, the implants almost always aid in communication. They are the treatment of choice for many with severe to profound sensorineural hearing loss.