Hearing allows you to be involved with the world around you. As a young child, you learned to speak by listening to and imitating the voices of others. Babies who are deaf have a hard time learning to speak clearly. You have learned most of what you know by listening to parents, teachers, television and radio. Music, the sounds of nature and the voices of loved ones can bring you pleasure; sirens and alarms can warn you about danger, even when you are asleep.
The human ear is divided into 3 parts -- the external, middle and inner ear. The inner ear is located inside the skull. It is the most complex part of the ear. The soft tissue of the inner ear is made of different types of cells and nerves, all arranged in a pattern on a thin sheet of tissue. Large tubes filled with fluid surround the soft tissue of the inner ear. Hearing loss occurs when the inner ear is damaged.
Aging, some drugs, head injuries and too much noise can all cause lasting damage to hearing. This handout discusses the most common type of permanent hearing loss -- the loss that results from too much noise.
Frequent exposure to loud or moderately loud noise over a long period of time can damage the soft tissue of the inner ear. Cells and nerves in the inner ear are destroyed by continuous or repeated exposure to loud sounds. If enough cells and nerves are destroyed, hearing is permanently damaged.
Whether noise harms your hearing depends on the loudness, the pitch and the length of time you are exposed to the noise. The loudness of a sound (measured in decibels, or dB) and the length of exposure are related. The louder the sound, the shorter the exposure can be before damage occurs. For example, 8 hours of exposure to 85-dB noise on a daily basis can begin to damage a person's ears over time. Using power tools (at about 100 dB), listening to loud stereo headsets (at about 110 dB), attending a rock concert (at about l20 dB) or hearing a gunshot (at 140 to 170 dB) may damage the hearing of some people after only a few times.
One reason people fail to notice the danger of noise is that too much exposure to noise causes few symptoms. Hearing loss is rarely painful. The symptoms are usually vague feelings of pressure or fullness in the ears, speech that seems to be muffled or far away, and a ringing sound in the ears that you notice when you are in quiet places. These symptoms may go away minutes, hours or days after the exposure to noise ends.
People assume that if the symptoms go away, their ears have "bounced back" to normal. This is not really true. Even if there are no more symptoms, some of the cells in the inner ear may have been destroyed by the noise. Your hearing returns to normal if enough healthy cells are left in your inner ear. But you will develop a lasting hearing loss if the noise exposure is repeated and more cells are destroyed.
The first sign of a noise-induced hearing loss is not hearing high-pitched sounds, like the singing of birds, or not understanding speech when in a crowd or an area with a lot of background noise. If the damage goes on, hearing declines further, and lower pitched sounds become hard to understand.
The following signs should be a red flag that the noise around you is too loud:
Written by familydoctor.org editorial staff