Noise-Induced Hearing Loss

Overview

Every day, we experience sound in our environment — from television and traffic to household appliances and music. Most of these sounds are safe. But sounds that are too loud, even for a brief time, or that are both loud and long-lasting can permanently damage sensitive structures in the inner ear and cause noise-induced hearing loss. The louder the noise, the faster it can damage your hearing.

Noise-induced hearing loss can happen to anyone at any age. It can be immediate or take a long time to become noticeable, and it can affect one ear or both ears. Because the damage from noise exposure is usually gradual, you might not notice it — or you might ignore the early signs until they become more serious.

The good news is that noise-induced hearing loss is preventable. By understanding the hazards of noise and practicing good hearing habits, you can protect your hearing. Teaching children to protect their hearing early can protect their hearing for life.

Signs and Symptoms

Noise-induced hearing loss can result from extremely loud bursts of sound, such as gunshots or explosions, which can rupture the eardrum or damage the bones in the middle ear. This kind of noise-induced hearing loss can be immediate and permanent.

Noise-induced hearing loss can build slowly over time. In this case, you might not notice the early signs of hearing loss. As hearing gets worse, certain sounds — particularly speech — begin to sound muffled. You may also experience the following:

• Asking others to repeat what they have said more often
• Turning up the sound on the TV, music player, or other devices
• Ringing or buzzing in the ears, a condition called tinnitus
• Trouble hearing high-frequency speech sounds, like some consonants
• Speech and music that sound muffled or distorted

Here are some simple rules of thumb to tell if the sounds around you are too loud:

• You find yourself speaking loudly or shouting so people an arm’s length away can hear you
• The noise hurts your ears
• Your ears buzz or ring during or after the noise goes away

Causes and Risk Factors

Three key factors affect whether and by how much a sound will damage your hearing:

• How loud the sound is
• How close you are to the source of the sound
• The length of time you are exposed to the sound

How Loud is Too Loud?

Sound is measured in units called decibels (dB). The decibel scale works differently than other units. An increase of 10 dB seems about twice as loud to your ears, but it is actually 10 times more intense. Because people cannot hear all frequencies, or pitches of sound, we often use A-weighted decibels (dBA) to describe sound intensity based on what human ears can hear.

Sounds at or below 70 dBA, even after long exposure, are unlikely to cause hearing loss. However, long or repeated exposure to sounds at or above 85 dBA can cause hearing loss. The louder the sound, the shorter the amount of time it takes for noise-induced hearing loss to happen.

Noises are more likely to damage your hearing if they are:

• 85 dBA and last a few hours
• 100 dBA and last at least 14 minutes
• 110 dBA and last at least 2 minutes

Here are the average decibel ratings of some familiar sounds:

• Normal conversation: 60–70 dBA
• Movie theater: 74–104 dBA
• Lawnmowers: 80–100 dBA
• Motorcycles and dirt bikes: 80–110 dBA
• Music through headphones at maximum volume, sporting events, and concerts: 94–110 dBA
• Sirens from emergency vehicles: 110–129 dBA
• Fireworks displays: 140–160 dBA

Sometimes exposure to loud noise causes a temporary hearing loss that disappears within a day or two. Recent research suggests, however, that although the loss of hearing seems to disappear, there may be residual long-term damage.

Who Is at Risk

Exposure to harmful noise can happen at any age. Some people — based on genetics or other factors — may be more sensitive to noise-induced hearing loss at even lower decibel levels.

Common Risky Activities

A one-time exposure to an intense “impulse” sound, such as an explosion, can cause noise-induced hearing loss. Continuous exposure to loud sounds over an extended period, such as loud music or noise generated in a woodworking shop can also cause noise-induced hearing loss.

Workplace noise poses a significant risk. The National Institute for Occupational Safety and Health (NIOSH) says that workers regularly exposed to sounds at or above 85 dBA are more likely to develop noise-induced hearing loss and should wear hearing protectors. Even below 85 dBA, some workers can still develop hearing damage.

Recreational activities can also put you at risk for noise-induced hearing loss. These activities include:

• Listening to loud music through headphones, at a concert, or while playing an instrument
• Going to movies in theaters
• Turning up the volume on the TV at home
• Attending sporting events with large, noisy crowds
• Attending fireworks shows
• Target shooting and hunting
• Snowmobile riding
• Working with loud power tools such as woodworking tools
• Using lawnmowers or leaf blowers

Prevention Guidance

Noise-induced hearing loss is the only type of hearing loss that is preventable. If you understand the hazards of noise and how to practice good hearing health, you can protect your hearing for life.

The best ways to protect your hearing are to avoid exposure to loud sounds, move away from the noise, or turn down the volume. When these options are not possible, wear hearing protectors such as earplugs or protective earmuffs.

You can also:

• Know which noises can cause damage
• Protect the ears of children who are too young to protect their own
• Make it a habit to wear hearing protectors when you expect to be in a loud setting, and keep earplugs or protective earmuffs handy for unexpected loud noises
• If loud noise happens suddenly or unexpectedly, cover your ears with your hands and move away from the noise, if possible

Treatment and Management

Over time, noise-induced hearing loss may make sounds seem distorted or muffled, and you might find it difficult to understand people when they talk. The damage from noise-induced hearing loss, especially when combined with aging, can lead to hearing loss severe enough that a person needs hearing aids.

Have your hearing tested if you think you might have hearing loss.

For people with hearing loss, hearing aids can amplify the sounds around them to help them hear, communicate, and participate more fully in daily activities. Other technologies such as assistive listening devices are also available. See the Healthy Hearing page for more information.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on noise-induced hearing loss.

Find Treatment

Consult a hearing health professional if you need help selecting hearing protection, or for information about custom-made earplugs. They can also help screen for and assess hearing loss. If needed, they can also help you get hearing aids.

Over-the-counter (OTC) hearing aids are also available. They are intended to help adults with perceived mild to moderate hearing loss. Like prescription hearing aids, over-the-counter hearing aids make sounds louder so that some adults with difficulty hearing are better able to listen, communicate, and participate fully in daily activities.

Community Support

The NIOSH Sound Level Meter App is a free app for iOS devices to measure sounds in your environment.

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.

NIH supports research on the causes, diagnosis, treatment, and prevention of hearing loss. Researchers have helped to identify some of the many genes important for hair-cell development and function and are using this knowledge to explore new treatments for hearing loss.

Researchers are also looking at the protective properties of supporting cells in the inner ear, which appear to be capable of lessening the damage to sensory hair cells upon exposure to noise.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.