The Five Senses and Beyond: The Encyclopedia of Perception - Jennifer L. Hellier 2017

Cochlear Implants

Cochlear implants are used in patients who are extremely hard of hearing or deaf as a treatment for deafness caused by damage to the sensory hair cells within the cochlea, which transmit vibrations to the brain via the auditory nerve. Rather than amplifying the sound as hearing aids do, cochlear implants perform the same function as the sensory hair cells within the cochlea: they both amplify vibrations and transmit them to the auditory nerve, which makes up part of the vestibulocochlear nerve (cranial nerve VIII). Cochlear implants are electronic devices with both an external portion and an internal portion. Cochlear implants do not transmit the same sound that would be heard by someone with normal hearing; rather, they offer a close enough facsimile that the patient can interact with his or her environment and participate in conversations. Surgery is required to install the implant.

How the Implants Work

Cochlear implants bypass the damaged portions of the patient’s ear to directly stimulate the auditory nerve. To do this, the cochlear implant uses four major parts: (1) a microphone—responsible for catching any noises from the external environment; (2) a speech processor—determines which sounds are to be amplified and how; (3) a transmitter—converts those noises allowed through the microphone and speech processor into electrical impulses the brain will recognize; and (4) an electrode array—a group of electrodes that collects the impulses from the transmitter and sends them to the auditory nerve to travel to the brain. The auditory nerve then conducts this electrical signal primarily to the temporal nerve where the sound is converted into something the patient perceives as sound. Cochlear implants only work if the patient’s brain is capable of taking this electrical signal and converting it into what the patient hears as a sound. The sounds heard by the patient’s brain are not the same as normal hearing, but they still allow the patient to hear and react to noises in the environment, including carrying on a normal conversation.

Implantation and Treatment

The only way for cochlear implants to be installed is through expensive surgery—in 2010 the average cost of the cochlear implant, surgery, and postoperative aural rehabilitation was well over US$40,000. If the surgery is successful, patients still have to undergo extensive therapy to learn how to interpret the sound that they hear. Results are often the best for patients who fairly recently lost their hearing, as they can learn to associate certain sounds that they hear with sounds from before. Children who undergo early implantation also experience pretty good results with intensive postimplantation therapy. The U.S. Food and Drug Administration (FDA) has reported that approximately 324,200 people in the world have received a cochlear implant and approximately 58,000 U.S. adults and 38,000 U.S. children have received cochlear implants (NIDCD, 2013). The National Institute on Deafness and Other Communication Disorders (NIDCD) supports further research in the field of treatments for deafness, including the cochlear implant to improve its function. One group of studies is looking at ways to make the sound heard through the implant sound more like normal hearing and to convey speech in an easier to understand way. Additional research is also looking into ways to use the cochlear implant to treat a variety of other hearing losses.

Famous People with Cochlear Implants

There are a few famous persons who lost their hearing as a young child and have decided to undergo cochlear implant surgery. In 1999, Guiding Light actress Amy Ecklund received her cochlear implant (Ecklund, 1999). Ecklund lost her hearing at age six and was enrolled in drama classes to maintain her speaking ability. In 1995, she was hired to play deaf hospital administrator Abigail Bauer. After Ecklund received her cochlear implant, her character also underwent cochlear implant surgery. Former Miss America Heather Whitestone recovered her hearing with a cochlear implant in 2003. She was the first deaf woman to be crowned Miss America (1995) and is now the first Miss America alum to receive a cochlear implant. She decided to have the surgery after her son hurt himself in the backyard and was crying. Whitestone was inside and did not know that he was injured. This incident made her want to better connect with the hearing world.

Riannon C. Atwater

See also: Auditory System; Cochlea; Cranial Nerves; Deafness; Sensory Receptors; Vestibulocochlear Nerve

Further Reading

Ecklund, Amy. (1999). Now hear this! People, 52, 1. Retrieved from http://www.people.com/people/archive/article/0,,20128697,00.html

National Institute on Deafness and Other Communication Disorders (NIDCD). (2013). Cochlear implants. Retrieved from https://www.nidcd.nih.gov/health/hearing/pages/coch.aspx