Deafness is the complete loss of hearing, whereas hearing loss may be partial or complete. Deafness may be present from birth, as a result of many possible causes, or it may begin later in life as a result of age-related changes in the ear, disease, injury, or excessive exposure to noise.
Kathy Peck was a guitarist during the 1970s and 1980s in a rock band known as the Contractions. The band played a mix of punk and new wave music in San Francisco, and toured across the United States. The Contractions gained some critical and popular success, playing shows with groups such as Duran Duran. During the mid-1980s Kathy realized she was losing some of her hearing. All those years of playing loud music and attending concerts had damaged her ears, similar to what happened to musician Pete Townshend of the Who. When Kathy and a physician named F. Gordon attended an especially loud concert in 1988, they decided to take action. They started H.E.A.R. (Hearing Education and Awareness for Rockers), a group that aims to prevent hearing loss among musicians and their fans. H.E.A.R. promotes wearing earplugs to reduce loud music to a level that does not damage the ear.
Rock music is not the only cause of noise-related ear damage. Excessive exposure to power tools and other forms of machinery is one of the most common causes of deafness and hearing loss in the United States. According to the National Institute on Deafness and Other Communication Disorders, one in eight people in the United States (13 percent, or 30 million) age 12 years or older has hearing loss in both ears, based on standard hearing examinations.
The different parts of the ear all facilitate hearing. The pinna is the fleshy, visible part of the outer ear that captures the sound waves. It directs these waves down a short tunnel, called the ear canal. The canal ends at the eardrum, which vibrates when sound waves reach it.
The eardrum is attached to three tiny bones called the ossicles which are located in the air-filled middle ear. The vibrating eardrum causes the ossicles that are connected to it to begin vibrating as well. As the bones move, the sound waves are transferred through another thin layer of tissue into the inner ear.
The most complex action in the ear occurs in the inner ear, deep within the skull. The sound waves first enter the cochlea, which contains fluid and is lined with cilia (tiny strands of hair). The fluid in the cochlea begins to vibrate and causes the microscopic hairs to move. The movement of the hairs stimulates nerves that transfer sound information to various areas of the brain. The brain processes this information and interprets the signals as a particular word or sound.
Hearing loss can occur in varying degrees. Some people with deafness can hear no sounds at all. Others have partial hearing loss, which means they may have trouble hearing certain sounds unless someone is speaking closely to them. In addition, hearing loss can be unilateral (affecting only one ear) or bilateral (involving both ears). For some people, hearing loss is gradual and gets worse as time passes. In some cases, hearing loss may only be temporary, such as a buildup of earwax * . If the wax is removed properly by a health professional, hearing is restored. In other cases, total or partial hearing loss is permanent.
There are three types of hearing loss: conductive, sensorineural (sensor-ee-NOOR-al), and a mixed form that combines conductive and sensorineural hearing loss.
Conductive hearing loss occurs when sound is not conducted efficiently from the outer ear to the eardrum and middle ear. If sound is imagined as waves of water, then conductive hearing loss occurs when something creates a “dam” that blocks the waves. This dam can result from the buildup of earwax in the ear, water in the ear canal (experienced by swimmers), or an infection that causes part of the ear to malfunction. Other causes include damaged eardrums and abnormal bone growth.
Sometimes the eardrum gets a tear or hole in it, which causes it to lose some or all of its ability to vibrate properly. Such damage may occur if a cotton swab or other object is placed too far inside the ear or if an explosion, gunshot, or other extremely loud sound occurs too close to the ear; or as a result of an ear infection, a head injury, or a sudden or extreme change in air pressure.
The ossicles are the tiny bones in the middle ear that work together in a very small space to conduct sound from the eardrum to the inner ear. If they grow too much or too little, or are damaged, they cannot do their job well. This problem may be present from birth or it may occur as children grow.
Sensorineural hearing loss occurs when there is damage to the inner ear or the nerves that connect the inner ear and the brain. This is the most common type of permanent hearing loss. Some estimates suggest that about 90 percent of hearing loss results from sensorineural problems. It usually cannot be corrected medically or with surgery. However, this type of hearing loss can be treated with hearing aids or cochlear implants. Common forms of sensorineural hearing loss include presbycusis, damage to the cilia, genetic disorders, injuries, and Ménière's (men-YERZ) disease.
The most common cause of sensorineural hearing loss is change in the inner ear as people age. Called presbycusis (press-bi-KOO-sis), it starts gradually for many people when they are in their 40s or 50s. More than 50 percent of people age 75 and older have some form of presbycusis. Not all older people experience sensorineural hearing loss, but many do.
Sensorineural hearing loss can also be caused by damage to the cilia (SILL-ee-uh), the delicate hairs in the inner ear. Loud noises can damage the cilia, along with poor blood supply to the inner ear resulting from high blood pressure, heart disease, smoking, or poor nutrition. Infections, tumors, and some medications also may damage the cilia and nearby parts of the inner ear or nerves to the brain.
Genetic disorders may cause deafness from birth by interfering with the proper development of the inner ear or nerves to the brain. Injuries to the ear or head, such as a skull fracture, may cause sensorineural hearing loss.
Ménière's disease affects more than 3 million people in the United States, many of them between the ages of 30 and 60. It can cause sensorineural hearing loss, vertigo * and dizziness, and a ringing in the ears called tinnitus (TI-nuh-tus).
Mixed hearing loss involves any combination of conductive hearing loss and sensorineural hearing loss. For example, loud noise can damage the eardrum, which causes conductive hearing loss. However, loud noise can also damage the hairs in the inner ear, which is sensorineural hearing loss. If both occur, people are said to have mixed hearing loss.
Deafness and hearing loss are common, particularly among the elderly. According to the World Health Organization (WHO), 360 million people worldwide have disabling hearing loss, which is over 5 percent of the world's population. Approximately one-third of individuals aged 65 and older are affected by some degree of hearing loss.
At volumes above 110 decibels, hearing may become painful.
A volume above 120 decibels is considered deafening.
At volumes above 135 decibels, hearing will become extremely painful and hearing loss may result if exposure is prolonged.
At volumes above 180 decibels, hearing loss is almost certain with any exposure.
Deafness and hearing loss are not contagious, although some diseases that are contagious such as measles can cause hearing loss.
Hearing loss, or deafness present from birth, usually is first discovered by parents. They may begin to notice that loud sounds do not startle their baby or cause the baby to turn toward them. Hearing should be assessed no later than at one month of age. Many hospitals test infant hearing before the baby is discharged home with the parents. Babies found to have hearing deficits can be enrolled in special programs to help them learn alternative methods of communication. By school age, all children should have had their hearing tested, either by the family doctor or in school.
Hearing loss later in life is often not recognized at first. People may find they can hear almost as well by increasing the volume on the television set or by moving closer to or directly facing someone who is speaking, but they may not realize they are adapting this way. Other signs of hearing loss include asking people to repeat what they have said, complaining that other people are mumbling, misunderstanding what people have said, and not hearing the phone, doorbell, or voices calling from other rooms. Often the voices of women and children are the earliest sounds to be lost because the hair cells that recognize their higher pitched voices are the first to fail.
People with deafness and hearing loss usually learn to read lips and use sign language to communicate. Other ways to improve activities of daily living include the following:
Doctors use several tests to diagnose hearing loss. First, the doctor will examine the ear to look for possible causes of hearing loss such as earwax, inflammation, or structural abnormalities. They may also administer hearing tests. One test requires patients to listen with earphones for a variety of tones and then to signal when they hear them and to signal again when they hear them disappear. A related test involves a special device placed behind the ear that transmits tones directly to the inner ear through a portion of the skull called the mastoid. If these tones are recognized more easily than those from the earphone test, the hearing problem is in the middle ear. Another test involves understanding various words as they are spoken through earphones.
Treatment for deafness depends on the cause and severity of hearing loss. Treatment for earwax buildup or infections can reverse some forms of hearing loss. Surgery to repair damaged eardrums or the bones of the middle ear is also possible.
The most common device used to amplify sound is the hearing aid. Hearing aids come in various forms that fit in or behind the ear and can help make sounds louder and clearer. They cannot restore lost hearing completely, but they can make it easier for many people to hear sounds. Audiologists are trained specialists who help select, fit, and monitor the use of hearing aids for both children and adults.
Another type of treatment is the cochlear (KO-klee-ur) implant, which is a complex device that replaces the work of the delicate hair cells (cilia) of the inner ear. A receiver worn behind the ear captures sound waves and transmits them to a receiver placed surgically inside the skull. This receiver then stimulates the nerves the brain uses to interpret sounds. The surgery can be expensive, and it does not work for everyone, but for some it can be an effective way to restore partial hearing.
Some types of hearing loss can be prevented. Damage to the eardrum may be prevented by avoiding putting any objects (such as cotton swabs) in the ear, avoiding regular exposure to very loud sounds, and wearing protective devices such as earplug and noise-canceling headphones. Additionally, some forms of congenital and childhood hearing loss can be prevented by vaccinating children against diseases such as measles, rubella, and mumps, and vaccinating girls and women of childbearing age against rubella before pregnancy.
See also Aging • Dietary Deficiencies • Ear Disorders: Overview • Ear Infections (Otitis) • German Measles (Rubella) • Infection • Tinnitus • Tumor • Vertigo
Burkey, John M. The Hearing-Loss Guide: Useful Information and Advice for Patients and Families. New Haven, CT: Yale University Press, 2015.
Carmen, Richard E., ed. The Consumer Handbook on Hearing Loss and Hearing Aids: A Bridge to Healing. 4th ed. Sedona, AZ: Auricle Ink, 2014.
Fligor, Brian J. Understanding Childhood Hearing Loss: Whole Family Approaches to Living and Thriving. Lanham, MD: Rowman and Littlefield, 2015.
Centers for Disease Control and Prevention. “Hearing Loss in Children.” http://www.cdc.gov/NCBDDD/hearingloss/screening.html (accessed April 19, 2016).
World Health Organization. “Deafness and Hearing Loss.” http://www.who.int/mediacentre/factsheets/fs300/en/ (accessed April 19, 2016).
American Society for Deaf Children. 800 Florida Ave. NE, #2047, Washington, DC 20002-3695. Toll-free: 800-942-2732. Website: http://www.deafchildren.org (accessed April 19, 2016).
American Speech-Language-Hearing Association. 2200 Research Blvd., Rockville, MD 20850-3289. Telephone: 301-296-5700. Website: http://www.asha.org (accessed April 19, 2016).
H.E.A.R. Hearing Education and Awareness for Rockers. PO Box 460847, San Francisco, CA 94146. Website: http://www.hearnet.com (accessed April 19, 2016).
National Institute on Deafness and Other Communication Disorders, National Institutes of Health. 31 Center Dr., MSC 2320, Bethesda, MD 20892-2320. Telephone (voice): 301-496-7243. Telephone (TTY): 301-402-0252. Website: http://www.nidcd.nih.gov (accessed April 19, 2016).
* earwax is the waxlike substance in the ear that traps dust and other particles to prevent them from damaging the inner ear. Also known as cerumen (suh-ROO-men).
* vertigo (VER-ti-go) is the feeling that either the environment or one's own body is revolving or spinning, although neither is.