The cochlear implant is a surgically implanted device that transmits coded electrical impulses to stimulate the hearing nerve within the inner ear. It is used to provide partial hearing to children and adults who receive little or no benefit from hearing aid technology.

The cochlear implant has both internal (implanted) and external (worn outside the body) parts. An external microphone (usually mounted at ear level) picks up speech and other sounds in the environment. This sound is then converted into electrical signals by a sophisticated processing unit, called a speech processor, which is about the size of a small Walkman worn outside the body, or located on a BTE-like attachment worn on the ear. The electrical signals are transmitted through the skin to an internal receiver, which has been surgically implanted. There, the signals are sent to an array of electrodes implanted in the cochlea (inner ear) to stimulate the auditory nerve. The auditory nerve then sends these electrical signals to the brain. With extensive training, the brain learns to recognize/interpret these signals as sound. Once the implant site has healed after surgery, the speech processor requires programming or “mapping” to meet the auditory needs of the user. (Adapted from Understanding Cochlear Implants, by MED-EL Corporation.)

The cochlear implant differs from a hearing aid in that it does not make sounds louder. Instead, it bypasses the non-functioning parts of the inner ear and electronically stimulates the remaining hair cells to produce a sensation of sound.

A cochlear implant does not provide the user with normal hearing. However, results reported with today's cochlear implants consistently indicate speech understanding for the majority of implanted patients. (Adapted from "Understanding Cochlear Implants" by the MEDEL Corporation) The benefits of the cochlear implant vary from person to person and depend on a variety of factors, such as:

· Age at onset of deafness,
· Age at implant surgery,
· Pre-implant duration of deafness,
· Age-appropriate sign or spoken language competence,
· Previous listening experience,
· Family support and motivation of the individual,
· Condition of the cochlea,
· Consistency of usage,
· Cochlear implant technology,
· Appropriate programming of device,
· Additional special needs,
· The quality and consistency of educational and habilitative environment, and
· The quality and consistency of post-implant training and support.

(Adapted from the article, “The Benefits and Limitations of Cochlear Implants” prepared by the Laurent Clerc National Deaf Education Center at Gallaudet University)

The US Food and Drug Administration (FDA) has approved several devices for use in children ages 12 months - 17 years, who meet the criteria, regardless of the age at which they lost their hearing. In order to be considered for implantation, children must receive an extensive evaluation by a team of specialists. To be a candidate for a cochlear implant, a child must have a profound sensorineural hearing loss in both ears. The average hearing level in the speech frequency range (500 to 2000 Hz.) must be 90 decibels or poorer in both ears without hearing aids, and with hearing aids the child must not be able to clearly recognize single words out of context without looking at the speaker’s face. If the child has less than a severe/profound hearing loss, these devices are generally not recommended and a properly fitted hearing aid can be as effective.

Children with implants must receive intensive and ongoing therapy in order to maximize the use and potential of the cochlear implant. Cochlear implants do not eliminate the need for a specialized educational program for the child. Each child’s progress and amount of benefit varies.

A cochlear implant is very expensive. However, with FDA approval, many insurance carriers will provide full or partial coverage. Most cochlear implant companies also employ specialists who resolve insurance disputes over coverage reimbursements.

Cochlea Illustration: Cochlear.com

Related Links: Advanced Bionics , Cochlear, MED-EL

American Speech Language Hearing Association - New Directions in Cochlear Implantation

Boys Town National Research Hospital

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