Aging and excessive exposure to loud noise are the most common causes of hearing loss. Other factors—such as viral or bacterial infections, an inherited disorder, or a benign tumor in the ear—also can produce hearing loss. One in 10 people in the United States has a hearing loss severe enough to affect his or her ability to hear normal speech. After age 50, most people have some degree of hearing loss. The changes occur very gradually and usually go unnoticed until a family member or friend mentions the person's hearing problems. Among older people, a third of those between ages 65 and 74 and half of those over age 85 have hearing loss.
There are two main types of hearing loss: conductive hearing loss and sensorineural hearing loss. Conductive hearing loss occurs when something, such as a buildup of earwax or an abnormality in the eardrum, prevents sound waves from being transmitted to the inner ear. This type of hearing loss can sometimes be corrected with medication or surgery. Sensorineural hearing loss refers to hearing problems that occur because of damage to the inner ear or the auditory nerve. Such damage can occur as a result of the aging process or because of exposure to loud noise. A hearing aid (see page 399) is most helpful for this type of hearing loss.
Exposure to loud noises—either a one-time exposure or repeated exposure over time—damages both the sensory hair cells of the inner ear and the auditory nerve. The longer you are exposed to loud noise and the closer you are to its source, the more damage it can cause.
The loudness of sound or noise is measured in units called decibels. A ticking watch is about 20 decibels, normal conversation is about 60 decibels, and city traffic noise is about 80 decibels. Sounds at 80 decibels or less are considered safe. Sounds between 90 and 100 decibels, such as a rock concert or a jet engine, may damage your hearing. Sounds that are between 120 and 140 decibels are usually painful and even a brief exposure can cause permanent hearing loss. Examples of things that can produce sounds over 120 decibels include motorcycles, snowmobiles, jackhammers, firecrackers, woodworking tools, and firearms.
Exposure to loud noise can occur in the workplace, in recreational settings, and at home. Some people are more sensitive to noise than others. In general, however, noise is loud enough to affect your hearing if you have to shout over it to be heard or if the noise causes pain or ringing in your ears. Temporary hearing loss that lasts for a few hours after exposure to loud noise is a sign of damage to your hearing.
For some people with hearing loss, sounds may gradually become distorted or muffled. They may experience problems having a conversation, listening to music, or even hearing a ringing doorbell or telephone. Participating in daily activities may become more difficult and less enjoyable because the person cannot hear properly and feels left out. He or she also may hear a hissing or a ringing in the ears (tinnitus; see page 401). Hearing loss also may have psychological effects. The person may become a source of annoyance or frustration and be ridiculed or ignored by family and friends. He or she might become depressed or withdraw from others to avoid embarrassment.
Although noise damage to the inner ear is irreversible, there are steps you can take to prevent noise-induced hearing loss. The most important thing you can do to protect your hearing is to avoid loud noise whenever possible. It is a good idea, for example, to keep the volume low on your personal stereo. If other people can hear music coming from your headphones, the sound is probably loud enough to cause permanent damage to your hearing.
If you are exposed to loud noise in the workplace, be sure to wear appropriate ear protection. Using specially designed earmuffs is the most effective way to protect your hearing on the job. These earmuffs, which resemble stereo headphones, block out almost all sound. Usually they are worn by people who work around noisy equipment or under extremely noisy conditions, such as construction workers or airport baggage handlers.
Another effective form of ear protection (although less effective than ear-muffs) is earplugs made of foam rubber, plastic, or wax. Earplugs are inserted into the outer ear canal and must fit snugly to provide optimal protection. They should be replaced promptly if they become soiled or worn, because they will quickly lose their effectiveness. Ordinary cotton balls cannot adequately protect your hearing. You can purchase earplugs in a variety of styles, shapes, and sizes at your local pharmacy.
If your workplace is very noisy, it is extremely important that you have your hearing checked regularly. If your employer does not have your hearing checked regularly, see your doctor, who will perform hearing tests (see "Diagnostic Procedures," page 404) to check for hearing loss. If hearing loss is detected early, you can take steps to prevent further damage to your ears. If noise levels at work seem too high, talk to your employer or your union representative. You may also contact your local health department or the local office of the Occupational Safety and Health Administration (OSHA) to report the problem.
If you think you may have hearing loss, see your doctor. He or she will perform audiometry (see page 404) using an instrument called a screening audiometer to test your hearing. This instrument produces a range of sound tones at various frequencies and volumes that are typically heard during speech. The doctor will ask you to raise your finger each time you hear a tone. The results of this test will determine whether your hearing loss is serious enough for your doctor to refer you to an audiologist, a health professional trained in evaluating hearing 399
loss and fitting hearing aids (see below), or an otolaryngologist, a physician who Ears specializes in treating disorders of the ear, nose, and throat.
Do You Have Hearing Loss?
Hearing loss is common, especially among older people. You may have some degree of hearing loss if any of the following apply to you:
• You have difficulty hearing over the telephone.
• You have difficulty following a conversation when two or more people are talking at the same time.
• Friends and family complain that you turn the TV up too loud.
• People often ask if you can hear them.
• You strain to understand conversations.
• You have difficulty hearing over background noise.
• You think that other people are mumbling when they speak.
• You have difficulty hearing someone who is whispering.
• You have difficulty hearing women or children talking.
If you have any of these problems, talk to your doctor. He or she can perform a simple hearing test to determine whether you have hearing loss and may refer you to an oto-laryngologist or an audiologist for additional testing.
A hearing aid is a small, battery-powered device that fits in or over your ear and amplifies sounds. Although a hearing aid can be fitted to only one ear, hearing aids are usually placed in both ears to provide the best overall hearing. Amplification of sound in both ears allows the person to hear speech more clearly and helps him or her to distinguish where sounds are coming from, especially in noisy surroundings.
Although many models of hearing aids are available, most can be placed into one of the following categories. Behind-the-ear hearing aids fit over the ear and are connected to a custom-made earpiece. In-the-ear hearing aids sit inside the outer ear and the outer part of the ear canal. In-the-canal hearing aids are small, unobtrusive devices that fit inside the ear canal. The smallest and least visible devices are completely-in-the-canal hearing aids, which fit more deeply inside the ear canal. In-the-canal hearing aids and completely-in-the-canal hearing aids are the most cosmetically appealing because they provide powerful assistance to hearing without being visible. Many hearing aids also come with telephone pickup switches that provide special assistance while you are on the phone or listening to a public sound system. The type of hearing aid that is right for you
Concerns depends on your degree of hearing loss, the size and shape of your ear and ear canal, your lifestyle, and your budget.
Custom-made hearing aids vary in price, depending on style and special features. Prices typically range from $500 for a standard hearing aid up to $2,500 for hearing aids that are fully computerized and programmable. However, price should not be your only consideration when choosing a hearing aid. You should also consider factors such as comfort, appearance, durability, reliability, and the service agreement.
Before choosing a hearing aid, you should have a thorough hearing evaluation (see "Diagnostic Procedures," page 404) performed by an otolaryngologist or an audiologist. You can purchase the hearing aid directly from the doctor or the audiologist or from an independent, licensed hearing aid distributor. A wax impression of your ear will be made so that the laboratory can create a hearing aid that fits your ear exactly. No matter where you purchase your hearing aid, however, it is essential to have it custom-fitted to your ear for best results. It is important to note that hearing aids purchased through mail order usually cannot be custom-fitted.
When you receive your hearing aid, you will be tested to determine how well you can hear and understand speech while wearing the device. You will also learn how to care for your hearing aid, how to insert and remove it, how to change the batteries, and how to use your hearing aid correctly. You will need to have your hearing aid tested and adjusted regularly to ensure that it is working properly. Once you begin wearing your hearing aid, give yourself time to adjust. You should begin by wearing the device first in quiet surroundings and gradually work up to noisier situations. Although a hearing aid cannot cure your hearing loss, it can allow you to hear sounds and voices more clearly so that you can communicate better and more easily participate in your usual activities.
Almost all people with hearing loss can benefit from using a hearing aid. Others, however, may need surgery to improve their hearing. Here are some surgical procedures that are performed to treat hearing loss:
• Myringoplasty. This procedure is used to repair a perforated eardrum (a hole in the eardrum) with a tissue graft (a transplantation of healthy tissue from one part of the body to another). The tissue is usually taken from another part of the ear, or from an area near the ear. The procedure is often performed using local anesthesia and causes a minimal amount of pain. The person may need to stay overnight in the hospital and will need to rest at home for about a week after surgery. In most cases, recovery is complete in about 6 weeks.
• Tympanoplasty and stapedectomy. These procedures are used to repair a perforated eardrum or to replace damaged bones in the middle ear. Damaged bones may be repaired, or they may be replaced with artificial implants, trans-
planted bones supplied by a donor, or bones constructed from cartilage. The 401
procedure is performed using either local or general anesthesia and may cause Ears mild pain for a few days. The person may not need to stay overnight in the hospital but will need to rest at home for about 7 to 10 days after surgery. In most cases, recovery is complete in about 2 months. • Cochlear implant. This procedure involves implantation of an electronic device to treat severe sensorineural hearing loss (see page 397) that has caused total or near-total deafness. The implant changes sound waves into electronic impulses that are carried along the auditory nerve to the hearing center in the brain, enabling the person to distinguish different kinds of sounds and often to understand speech. The device has both internal and external components. The internal component (a special signal processor and electrodes) is surgically implanted into the ear while the person is under general anesthesia. The person usually needs to stay in the hospital for a couple of days. The ear will heal in about 4 to 6 weeks, after which the physician will fit the person with the external components (a microphone, a transmitting coil, a speech processor, and connecting wires). The person will then work with an audiologist to adjust the settings on the implant for the best hearing level and to learn how to use the device properly.
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