Start here: how hearing works

NIOSH’s occupational recommendation is 85 dBA averaged over an 8-hour workday, with a 3 dB exchange rate: 88 dBA for 4 hours or 91 dBA for 2 hours reaches the same recommended daily dose. These are workplace recommendations, not guaranteed safe listening times for everyone or all activities. CDC/NIOSH

General environmental-noise guidance and personal-audio listening allowances use different averaging periods. Compare NIOSH, EPA, and WHO guidance.

The decibel level and time of exposure are the most important considerations, referred to as our exchange rate. Some sounds — such as gunfire, explosions, etc. — are so loud (140 or more decibels), that ANY brief exposure to them at close range can cause permanent damage and hearing loss. Sounds at 100 decibels (such as loud music through stereo headphones) will take a while longer to cause permanent damage to hair cells in the cochlea. The frequency of the sound is less important than its decibel level and time of exposure.

Both sound level and exposure time matter. NIOSH’s occupational recommendation is 85 dBA as an 8-hour time-weighted average, not a guaranteed safe period for every person or activity. Each 3 dBA increase halves the time to the recommended daily dose. CDC/NIOSH

A single intense impulse, such as an explosion or gunshot, can cause immediate damage; repeated exposure to loud sound can also damage hearing over time. NIH/NIDCD

Examples include lawn mowers (about 80–100 dB), sporting events (94–110 dB), concerts or nightclubs (95–115 dB), and fireworks (140–160 dB). These ranges are approximate; actual exposure depends on conditions, distance, and duration. CDC sound examples

Loud sound can cause damage through a single intense impulse or repeated exposure over time. NIH/NIDCD

• The effect from sound can be instantaneous and can result in an immediate hearing loss that may be permanent.
• The structures of the inner ear may be severely damaged. This kind of hearing loss may be accompanied by tinnitus (an experience of sound like ringing, buzzing or roaring in the ears or head) which may subside over time. Hearing loss and tinnitus may be experienced in one or both ears, and tinnitus may continue constantly or intermittently throughout a lifetime.
• The damage that occurs slowly over years of exposure to loud noise is accompanied by various changes in the structure of the hair cells. It also results in hearing loss and tinnitus.
• Exposure to impulse and continuous noise may cause only a temporary hearing loss. If the hearing recovers, the temporary hearing loss is called a temporary threshold shift. The temporary threshold shift largely disappears within 16 hours after exposure to loud noise.
• Hearing that does not recover is because permanent damage has occurred. This hearing loss is permanent.
• Both forms of NIHL can be prevented by the regular use of hearing protectors such as earplugs or earmuffs.

Damage can be apparent immediately, or it can gradually become noticeable. Because the majority of hearing impairment comes on gradually, this makes it more difficult to notice that damage has taken place.

This is a fancy way of saying temporary hearing loss. After a loud concert or sporting event, your hearing is temporarily reduced. After about 16 to 18 hours, this resolves and your hearing should return to the level it was before (hopefully normal). Often the hearing is reduced, there is frequent tinnitus, which is especially noticed in quiet places such as when you are trying to sleep. The tinnitus and hearing loss (sometimes felt as a numbness in your ears) should completely resolve after 16 hours.

The symptoms of NIHL that occur over a period of continuous exposure increase gradually. Sounds may become distorted or muffled, and it may be difficult for the person to understand speech. The individual may not be aware of the loss, but it can be detected with a hearing test.

More than 30 million Americans are exposed to hazardous sound levels on a regular basis. Individuals of all ages including children, adolescents, young adults and older people can develop NIHL. Exposure occurs in the workplace, in recreational settings and at home. There is an increasing awareness of the harmful noises in recreational activities, such as, concerts, sporting events, target shooting or hunting, snowmobiles, lawnmowers, go-carts, woodworking and other hobby equipment. Harmful noises at home may come from vacuum cleaners, garbage disposals, lawn mowers, leaf blowers and shop tools. People who live in either urban or rural settings may be exposed to noisy devices on a daily basis. Of the 28 million Americans who have some degree of hearing loss, about one-third have been affected, at least in part, by noise.

Most people reach the age of 50 without any hearing problems, but others suffer a very slow and gradual hearing loss that may not be noticed for years. Certainly working in a noisy industry is one such cause. And listening to loud music is another. The ear is made up of three parts—the outer ear, the middle ear, and you guessed it, the inner ear. The inner ear is about the size of a small fingernail and contains about 15,500 nerve endings, called hair cells. When some of these hair cells are damaged, you have permanent hearing loss. Damage to the outer and middle ears is usually temporary and can be treated by a doctor.

Other than hearing loss associated with aging (Presbycusis), the most prevalent cause is working around noise and recreational activities. The ear does not know the difference between loud noise and loud music. To the ear, noise and music are just vibrations in the air. Rarely, a person may suffer a permanent hearing loss from a virus or even a brain tumor. These usually have a sudden onset and may be accompanied by dizziness. Hearing loss from noise or music tends to be gradual in nature with no dizziness.

Only hearing losses that are from the middle ear (where kids get ear infections) or from the outer ear (such as wax occlusion) can be treated. Rarely can a hearing loss be treated if it is from the inner ear. The inner ear is actually in the brain, so inner ear surgery is brain surgery. Having said this, researchers are working on a “vaccination” that can be given to reverse inner ear hearing loss.

Hearing loss comes with two other things that can be very annoying—or if you are a musician, career ending. They are pitch perception problems and permanent tinnitus. Pitch perception problems, as the name suggests, means that a person with a significant hearing loss may hear one note as another (and have limited understanding for speech). And can you imagine having a constant hum or whistle in your head day and night? This is what many people report with permanent tinnitus. So,…prevention of hearing loss is where it is at because YOUR EARS ROCK

Although this is uncommon, it does occur on occasion. There is almost always a hearing loss associated with tinnitus. Using a small hearing aid not only will help you hear better, it tends to mask or block out the tinnitus in the majority of people. Being overly concerned about it is another problem. The last thing someone should do is become stressed as this may make the tinnitus more noticeable. There are therapy programs that serve to retain the brain to ignore tinnitus and these can be very successful. Contact your local audiologist or doctor if this becomes a problem. Mobile-applications are also now available that allow you to customize tinnitus masking noise.

The scientific name is cerumen. Wax in the ears is a common and easily treatable cause of deafness, discomfort, and sometimes noises in your ears (tinnitus). The skin cells lining our outer ear canals include tiny glands, similar to sweat glands, which produce wax and acts as a protective layer, which traps dust and other particles which get into the ear. The wax slowly works its way to the outside, taking the trapped dirt and dust with it along with a scent that helps repel insects. Ear wax only causes problems when it builds up, which may be due to overproduction or difficulties in the natural clearance of the wax.

DO NOT clean your ears with a Q-Tip unless it is the outer portion of the ear (Pinna). Arrange to see a professional regarding having your ears washed out on a regular basis.

Scientists focusing their research on the mechanisms causing NIHL hope to understand more fully the internal workings of the ear, that will result in better prevention and treatment strategies. For example, scientists have discovered that damage to the structure of the hair bundle of the hair cell is related to temporary and permanent loss of hearing. They have found that when the hair bundle is exposed to prolonged periods of damaging sound, the basic structure of the hair bundle is destroyed and the important connections among hair cells are disrupted which directly lead to hearing loss.

Other studies are investigating potential drug therapies that may provide insight into the mechanisms of NIHL. For example, scientists studying altered blood flow in the cochlea are seeking the effect on the hair cells. They have shown reduced cochlear blood flow following exposure to noise. Further research has shown that a drug that promotes blood flow used for treatment of peripheral vascular disease (any abnormal condition in blood vessels outside the heart), maintains circulation in the cochlea during exposure to noise. These findings may lead to the development of treatment strategies to reduce NIHL.

Continuing efforts will provide opportunities that can aid research on noise-induced hearing loss as well as other diseases and disorders that cause hearing loss. Research is the way to develop new, more effective methods to prevent, diagnose, treat and eventually eliminate these diseases and disorders and improve the health and quality of life for all Americans.

There are four easy ways to protect yourself from Noise-Induced Hearing Loss (NIHL)

• Turn it down
• Wear hearing protection
• Create a distance between you and the sound source
• Limit your exposure time

Noise-induced hearing loss is in most cases preventable. All individuals should understand the hazards of noise and how to practice good health in everyday life.

• Know which noises can cause damage (those above 85 decibels).
• Wear ear plugs or other hearing protective devices when involved in a loud activity (special earplugs and earmuffs are available at hardware stores and sporting good stores).
• Be alert to hazardous noise in the environment.
• Protect children who are too young to protect themselves.
• Make family, friends and colleagues aware of the hazards of noise.
• Have a medical examination by an otolaryngologist, a physician who specializes in diseases of the ears, nose, throat, head and neck, and a hearing test by an audiologist, a health professional trained to identify and measure hearing loss and to rehabilitate persons with hearing impairments.