What are hearing aids?

Indications and Procedures

Hearing loss is one of the most common conditions affecting older adults, but it is not limited to that age group. According to the World Health Organization, disabling hearing loss affected more than 350 million people worldwide by 2013, with many more experiencing mild forms of hearing loss. The use of hearing aids is one of the primary strategies for the treatment of hearing loss. These devices were developed to help those people affected by hearing loss ranging from mild to severe and resulting from a number of causes. The most common type of hearing loss, sensorineural, is linked to a variety of physical and psychosocial dysfunctions (isolation, depression, hypertension, and stress) as well as illnesses such as ischemic heart
disease and arrhythmias.

Over the years, hearing aids have evolved in several ways. Two major trends have been in signal processing and size. Prior to the 1940s, hearing aids were large and required carrying a battery pack strapped to one’s body. In the 1940s, vacuum tubes reduced the size of hearing aids to that of a transistor radio. Hearing aids worn in the ear or on the head were not available until the 1960s. At that time, the best available hearing aids helped in quiet only; in loud situations, they made things worse. Therefore, it was common practice to remove them around noise. Beginning in the 1980s and 1990s, advanced circuitry offered consumers improved quality of hearing in quiet as well as some increased ability to hear in noise; sound distortion was minimal. In the decades since, hearing aids have become more comfortable and less noticeable. Certain hearing aids can be electronically adjusted for individual users; for example, they can be reprogrammed to accommodate increased hearing loss. Some hearing aids have volume controls, while others adjust automatically. Research has shown that consumers report greater satisfaction with sound quality than they did in the past, and people with hearing loss in both ears tend to be more satisfied with two hearing aids, enabling them to determine the direction of sounds.

For patients with bilateral profound sensorineural hearing loss, which does not respond to traditional hearing aids, a cochlear implant is now possible. A cochlear implant is an electronic prosthesis surgically implanted in the inner ear. It has external parts that are worn outside the ear, including a microphone, speech processor, headpiece antenna, and cable. It is not a hearing aid. A cochlear implant delivers electrical signals to the brain, where they are interpreted as sounds. Potential candidates for these implants include both children and adults in a wide age range. Generally, children should be at least eighteen months old, and many successful implant recipients are in their eighties. Adults who become deaf later in life and who have fully developed speech and language before their hearing loss have better results with the implant than do those who were born deaf or who lost their hearing early in life. It has been shown, however, that children who are born deaf but are given cochlear implants early in life can receive great benefit from them. In adults, the memory of sound appears to be one of the most important factors for success. For children, early implantation and placement in an educational program that emphasizes the development of auditory skills appear to be important factors for success.

Uses and Complications

One of the biggest impediments to hearing aid use is patient reaction to hearing loss. Many people try to cover up the fact that they have hearing difficulties, and when hearing loss is confirmed, they experience a wide range of emotions, from horror, denial, disbelief, and withdrawal to embarrassment, sadness, resentment, and gradual acceptance and coping. People’s coping skills and behavior patterns vary, in part because hearing loss generally occurs gradually and may take a long time to be recognized.

For those who embrace hearing aids, a variety of technological and cosmetic choices are available. A number of options exist regarding hearing aid style: behind-the-ear, custom in-the-ear, in-the-canal, and the smallest, the completely in-canal hearing aid. In addition to aesthetic considerations and sound fidelity, one’s anatomy and manual dexterity may dictate the style that is most effective and efficient. The degree of hearing loss and other medical conditions are also important factors when evaluating the best hearing aid.

Perspective and Prospects

Hearing aid technology has improved such that patients with mild to moderate hearing loss will be candidates for hearing aids and those with severe loss will be candidates for hearing aids or cochlear implants, depending upon how well they function with a particular device. Patients with profound hearing loss will benefit best from cochlear implants.

Initially, only those patients who were completely deaf in both ears were considered candidates for cochlear implants. With significant improvements in implant technology, however, the benefits gained by implanted patients, both children and adults, have markedly improved. This, in turn, has led to a broadening of criteria for implant patients. Select patients with severe hearing loss who receive some benefit from hearing aids are considered possible implant candidates.

Bibliography

A.D.A.M. Medical Encyclopedia. "Devices for Hearing Loss." MedlinePlus, July 7, 2011.

Biderman, Beverly. Wired for Sound: A Journey into Hearing. Toronto, Ont.: Trifolium Books, 1998.

Carmen, Richard, ed. The Consumer Handbook on Hearing Loss and Hearing Aids: A Bridge to Healing. 3d rev. ed. Sedona, Ariz.: Auricle Ink, 2009.

Carson-DeWitt, Rosalyn. "Hearing Loss." Health Library, September 10, 2012.

Dillon, Harvey. Hearing Aids. New York: Thieme, 2001.

National Institute on Deafness and Other Communication Disorders. "Hearing Aids." National Institutes of Health, June 7, 2010.

Romoff, Arlene. Hear Again: Back to Life with a Cochlear Implant. New York: League for the Hard of Hearing, 1999.

World Health Organization. "Deafness and Hearing Loss." World Health Organization, February 2013.