Cochlear Implant Fact Sheet

 

 

 

 

  

Cochlear implants are auditory devices surgically implanted into the cochlea (inner ear) to replace nerve cells that have been lost. The implant uses 16-24 electrodes to stimulate the auditory nerve with electrical signals the brain can interpret as sound.  The implant includes external components that convey sound from the environment to the electrodes implanted within the inner ear.

  

Cochlear implant technology generates patterns of nerve activity that imitate those of a normal ear for a broad range of sounds.  During surgery, a series of electrodes are implanted into the cochlea, or inner ear. After a post-surgery period of four to six weeks during which they cannot yet hear with the device, cochlear implant patients return to their clinic for an initial stimulation and mapping session with an audiologist.  Mapping refers to the process of adjusting the external speech processor for the individual.  At this time, the patient is fitted with the external components of the cochlear implant.  These components include a tiny microphone that picks up environmental sounds and transmits them to a speech processor, where mechanical sounds are converted into a processed electrical signal. A transmitter coil placed on the scalp behind the ear passes the signals to a receiver located under the scalp.  The signal then travels along a wire to the tiny electrodes implanted within the cochlea.  The electrodes send the signals from the cochlea along the auditory nerve to the brain.  This entire process happens in real time.

 

 

 

The benefits gained from a cochlear implant vary from individual to individual.  Many patients may regain as much as 30 – 50% of hearing in the implanted ear.  For every cochlear implant patient, there is a learning curve of months or years, involving close collaboration with an audiologist and family members.  CI patients need time to become accustomed to identifying sounds with the device. They typically benefit from hearing environmental sounds within four to six weeks of surgery, when they complete their initial stimulation session with their audiologist. Over a period of time, patients can learn to hear and identify voices, determine inflections and patterns, and then the brain can fill in some of the rest. Most children who are appropriate CI candidates are able to develop functional oral communication skills with the CI and even attend regular educational programs.   

 

 

 

 The implants provide sound information for adults and children who have been diagnosed with profound sensorineural hearing loss and are unable to hear conversational-level speech through the use of the most powerful hearing aids. 

 

 A range of cochlear implants are available from three manufacturers.  The Nucleus® line of devices is available through Cochlear Corporation (www.cochlearamericas.com), the Clarion® line of devices is available through Advanced Bionics Corporation (www.advancedbionics.com), and the MAESTRO® line of devices is available from MED-EL  (www.medel.com).

 

 

 

 The Department of Auditory Implants and Perception at the House Ear Institute researches methods for understanding and improving auditory prosthetic devices such as cochlear implants.  Researchers in this department created the Computer-Assisted Speech Training (CAST) tool from HEI, a software program that allows CI patients to conduct auditory rehabilitation from their home computer.  In addition to organizing professional conferences on the topic of auditory prostheses, the DAIP conducts multiple research projects that include an investigative research trial of the penetrating auditory brainstem implant (ABI), frequency mapping of the cochlear implant, and training effects in cochlear implants.