In the United States, hearing loss is the third most common chronic physical condition after high blood pressure and arthritis. It is more common than diabetes, vision trouble, or cancer. Not surprisingly, hearing loss is among the most common work-related illnesses. Over 11% of the working population has hearing difficulty, and nearly one out of four cases of worker hearing difficulty are caused by work-related exposures. These exposures include loud noise and chemicals causing damage to the inner ear (ototoxic chemicals). Ototoxic chemicals include organic solvents like trichloroethylene, heavy metals like mercury and lead, and asphyxiants like carbon monoxide.

Noise is considered loud and potentially harmful (hazardous) when it reaches 85 decibels or higher, or if a person has to raise his/her voice to speak with someone 3 feet away (arm’s length).

Scope of the Problem

• In the United States, hearing loss is the third-most common chronic physical condition among adults after hypertension and arthritis.
• About 12% of the U.S. working population has hearing difficulty.
• About 24% of the hearing difficulty among U.S. workers is caused by occupational exposures.
• About 8% of the U.S. working population has tinnitus (‘ringing in the ears’) and 4% has both hearing difficulty and tinnitus.

What causes Occupational Hearing Loss (OHL)?

• OHL can occur when workers are exposed to loud noise or ototoxic chemicals.
• Noise is considered loud (hazardous) when it reaches 85 decibels or higher, or if a person has to raise his/her voice to speak with someone 3 feet away (arm’s length).
• Ototoxic chemicals can cause OHL, make the ear more susceptible to the damaging effects of hazardous noise, or both. For example, a person taking certain ototoxic pharmaceuticals may lose hearing, become more susceptible to noise, or both. Ototoxic chemicals (and examples) include:
  • solvents (styrene, trichloroethylene, toluene)
  • metals and compounds (mercury compounds, lead, organic tin compounds)
  • asphyxiants (carbon monoxide, hydrogen cyanide)
  • nitriles (3-Butenenitrile, cis-2-pentenenitrile, acrylonitrile)
  • pharmaceuticals (certain antineoplastic agents)

How Many Workers are Exposed?

• About 22 million workers are exposed to hazardous noise each year.
• About 10 million workers are exposed to solvents and an unknown number are exposed to other ototoxicants.

What is OHL Surveillance?

OHL surveillance includes:

• Collecting worker hearing data, exposure data and related information for analysis;
• Estimating how many workers have hearing loss or related health outcomes and how many workers are exposed;
• Examining these estimates by industry and occupation; and
• Monitoring trends over time.

Noise is a significant source of hearing loss, but you can protect your hearing. An important first step is to understand how noise causes hearing loss.

Loud Noise Can Cause Hearing Loss Quickly or Over Time

Hearing loss can result from a single loud sound (like firecrackers) near your ear. Or, more often, hearing loss can result over time from damage caused by repeated exposures to loud sounds. The louder the sound, the shorter the amount of time it takes for hearing loss to occur. The longer the exposure, the greater the risk for hearing loss (especially when hearing protection is not used or there is not enough time for the ears to rest between exposures).

Here are some sources of loud noise that you may be exposed to. If you are repeatedly exposed to them over time, they can cause hearing loss.

Everyday Activities

• Music from smartphones and personal listening devices, particularly when the volume is set close to the maximum
• Fitness classes
• Children’s toys

Events

• Concerts, restaurants, and bars
• Sporting events, such as football, hockey, and soccer games
• Motorized sporting events, such as monster truck shows, stock car or road races, and snowmobiling
• Movie theaters

Tools and More

• Power tools
• Gas-powered lawnmowers and leaf blowers
• Sirens
• Firearms
• Firecrackers

Common Sources of Noise and Decibel Levels

Sound is measured in decibels (dB). A whisper is about 30 dB, normal conversation is about 60 dB, and a motorcycle engine running is about 95 dB. Noise above 85 dB over a prolonged period of time may start to damage your hearing. Loud noise above 120 dB can cause immediate harm to your ears.

The table below shows dB levels and how noise from everyday sources can affect your hearing.

The time estimates listed in the “Typical Response” column are based on the NIOSH exchange rate of 3 dB.

Sounds May Be Louder Than What You Hear

How loud something sounds to you is not the same as the actual intensity of that sound. Sound intensity is the amount of sound energy in a confined space. It is measured in decibels (dB). The decibel scale is logarithmic, which means that loudness is not directly proportional to sound intensity. Instead, the intensity of a sound grows very fast. This means that a sound at 20 dB is 10 times more intense than a sound at 10 dB. Also, the intensity of a sound at 100 dB is one billion times more powerful compared to a sound at 10 dB.

Two sounds that have equal intensity are not necessarily equally loud. Loudness refers to how you perceive audible sounds. A sound that seems loud in a quiet room might not be noticeable when you are on a street corner with heavy traffic, even though the sound intensity is the same. In general, to measure loudness, a sound must be increased by 10 dB to be perceived as twice as loud. For example, ten violins would sound only twice as loud as one violin.

The risk of damaging your hearing from noise increases with the sound intensity, not the loudness of the sound. If you need to raise your voice to be heard at an arm’s length, the noise level in the environment is likely above 85 dB in sound intensity and could damage your hearing over time.

Noise can damage hair cells, membranes, nerves, or other parts of your ear, causing temporary or permanent hearing loss. Learn how this happens so that you can prevent hearing loss.

Hearing Loss Can Be Temporary or Permanent

Hearing loss is a decrease in your ability to hear or understand speech and sounds around you. Hearing loss can happen when any part of the ear or the nerves that carry information on sounds to your brain do not work in the usual way. In some cases, hearing loss can be temporary. However, it can become permanent when vital parts of the ear have been damaged beyond repair. Damage to any part of the ear can lead to hearing loss.

Loud noise is particularly harmful to the inner ear (cochlea). A one-time exposure to extreme loud sound or listening to loud sounds for a long time can cause hearing loss. Loud noise can damage cells and membranes in the cochlea. Listening to loud noise for a long time can overwork hair cells in the ear, which can cause these cells to die. The hearing loss progresses as long as the exposure continues. Harmful effects might continue even after noise exposure has stopped. Damage to the inner ear or auditory neural system is generally permanent.

Damaged Hair Cells in Your Ears Can Lead to Hearing Loss

The average person is born with about 16,000 hair cells within their cochlea. These cells allow your brain to detect sounds. Up to 30% to 50% of hair cells can be damaged or destroyed before changes in your hearing can be measured by a hearing test. By the time you notice hearing loss, many hair cells have been destroyed and cannot be repaired.

After leaving a very loud event, such as a concert or football game, you may notice that you don’t hear as well as before. You might not hear whispers, sound might seem muffled, or you may hear ringing in your ears. Normal hearing usually returns within a few hours to a few days. This is because the hair cells, similar to blades of grass, will bend more if the sound is louder. But they will become straight again after a recovery period.

However, if loud noise damaged too many of the hair cells, some of them will die. Repeated exposures to loud noises will eventually destroy many hair cells. This can gradually reduce your ability to understand speech in noisy environments. Eventually, if hearing loss continues, it can become hard to understand speech even in quieter places.

Noise Can Also Damage Nerves in Your Ears

In addition to damaging hair cells, noise can also damage the auditory nerve that carries information about sounds to your brain. Early damage may not show up on your hearing test, but can create a ‘hidden hearing loss’ that may make it difficult for you to understand speech in noisy environments. The cumulative effect of noise affects how well you might hear later in life and how quickly you might develop hearing problems, even after exposure has stopped.

How Do We Hear?

We hear sound because of vibrations (sound waves) that reach our ears. We recognize those vibrations as speech, music, or other sounds.

Outer Ear
The outer ear—the part of the ear you see—funnels sound waves into the ear canal. The sound waves travel through the ear canal to reach the eardrum.

Middle Ear
The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones amplify, or increase, the sound vibrations and send them to the inner ear.

Inner Ear
The inner ear contains a snail-shaped structure filled with fluid called the cochlea. Sound vibrations create waves in the cochlear fluids. As the waves peak, they cause tiny hair cells (types of receptors that can detect sound) to bend, which converts the vibrations into electrical signals.

Auditory Nerve
The auditory nerve carries the electrical signals from the inner ear to the brain, which interprets the signals as sound that you recognize and understand.

In the U.S. workplace:

• About 22 million workers (17%) are exposed to hazardous noise each year;
• About 10 million workers are exposed to solvents, which can damage hearing; and
• An unknown number of workers are exposed to other ototoxic chemicals that can damage hearing.

There are workers in every industry sector that are exposed to noise or chemicals that can damage hearing, or both.

Among all noise-exposed workers, 19%have hearing impairment. Hearing impairment is hearing loss that impacts day-to-day activities, such as making it difficult to understand speech. However, some industry sectors such as Mining and Construction have even higher percentages of workers with hearing impairment.

• Almost all work-related hearing loss is permanent, and it can have a profound impact on quality of life.
• As hearing loss worsens, hearing and understanding others becomes increasingly more difficult, which can lead to isolation.
• Hearing loss is associated with cognitive (mental) decline and heart problems, such as high blood pressure and heart disease.
• Hearing loss is also strongly associated with depression.
• Ringing in the ears (tinnitus), which often occurs along with hearing loss, can disrupt sleep and concentration and is associated with both depression and anxiety.
• Safety can also be impacted at home and on the job.
• Income is typically lower among hearing-impaired workers than among workers with normal hearing.
• There are other effects, such as loss of enjoyment, when all of the sounds we want to hear (e.g., music, voice of loved one) become muted and lack quality.

Fortunately, with today’s hearing loss prevention strategies and technologies, work-related hearing loss can be entirely prevented.

• Find out if the noise in your workspace is hazardous.
  • If you have to raise your voice to speak with someone at arm’s length, then the noise is likely at a hazardous level. Or check the noise level using a sound level meter app on your phone, such as the NIOSH Sound Level Meter app.
• Reduce your noise exposure:
  • Reduce noise at the source of the noise. Use quieter equipment and keep equipment well maintained and lubricated.
  • Enclose the source of the noise or place a barrier between you and the source.
  • Increase the distance between you and the source of the noise.
  • Reduce your time in noisy areas.
  • Always wear hearing protection in noisy areas, and if using foam plugs, insert them correctly.
  • If you are listening to music or something else, keep the volume at a safe level and only listen in areas that are not noisy.
• Reduce or stop exposure to chemicals that may damage your hearing:
  • Use a less-toxic or non-toxic chemical.
  • Wear gloves, long sleeves and eye protection.
  • Wear a respirator or other protective equipment, as appropriate.
  • Read and follow all chemical safety instructions.
• Learn more about hearing loss prevention here.

Many workers receive an audiogram (hearing test) at some point, especially if they are in a hearing conservation program, but what do the results mean? This single page (two-sided) fact sheet contains important answers to frequent questions workers ask about their audiograms. It addresses why workers should get regular audiograms, how to understand the results, and why the results should be saved to help evaluate and maintain the worker's hearing. It also has some basic information on the causes of hearing loss and how to prevent it.

In the United States, hearing loss is the third most common chronic physical condition after high blood pressure and arthritis. Not surprisingly, hearing loss is among the most common work-related illnesses. Workers are faced with occupational noise hazards every day. This page provides guidelines and recommendations for employers and workers to help reduce risks from noise exposure in the workplace.

Did you know that within every industry sector, there are workers at risk for work-related hearing loss?

Why is prevention important?

• Almost all work-related hearing loss is permanent, and it can have a profound impact on quality of life.
• As hearing loss worsens, hearing and understanding others becomes increasingly difficult, which can lead to isolation.
• Hearing loss is associated with cognitive (mental) decline and heart problems, such as high blood pressure and heart disease.
• Hearing loss is also strongly associated with depression.
• Hearing loss can lead to loss of enjoyment, when all the sounds we want to hear (e.g., music, voice of loved one) become muted and lack quality.
• Ringing in the ears (tinnitus), which often occurs along with hearing loss, can disrupt sleep and concentration and is associated with both depression and anxiety.
• Hearing loss can impact safety at home and on the job.
• Income is typically lower among workers with hearing loss, than among workers with normal hearing.

Fortunately, with today’s hearing loss prevention strategies and technologies, work-related hearing loss can be nearly always prevented.

What can workers do to prevent work-related hearing loss?

• Find out if the noise in your workspace is hazardous.
  • If you must raise your voice to speak with someone at arm’s length, then the noise is likely at a hazardous level.
  • You can also check the noise level using a sound level meter app on your phone, such as the NIOSH Sound Level Meter app.
  • Ask your safety manager or direct supervisor to check the noise levels in your workplace, making sure they are below 85dBA.
• Reduce your noise exposure:

• • Take a break from the noisy activity.
  • Reduce noise at the source of the noise. Use quieter equipment and keep equipment well maintained and lubricated.
  • Enclose the source of the noise or place a barrier between you and the source.
  • Increase the distance between you and the source of the noise.
  • Reduce your time in noisy areas.
  • Always wear hearing protection in noisy areas, and if using foam plugs, insert them correctly.
  • If you are listening to music or something else, keep the volume at a safe level and only listen in areas that are not noisy.
• Reduce or stop exposure to chemicals that may damage your hearing:

• • Use a less-toxic or non-toxic chemical.
  • Wear gloves, long sleeves and eye protection.
  • Wear a respirator or other protective equipment, as appropriate.
  • Read and follow all chemical safety instructions.

Don't we lose our hearing as we age?

It’s true that most people’s hearing test gets worse as they get older. But for the average person, aging does not cause impaired hearing before at least the age of 60. People who are not exposed to noise and are otherwise healthy, keep their hearing for many years. People who are exposed to noise and do not protect their hearing begin to lose their hearing at an early age. For example, by age 25 the average carpenter has “50-year old” ears! That is, by age 25, the average carpenter has the same hearing as someone who is 50 years old and has worked in a quiet job.

Can you poke out your eardrums with earplugs?

That is unlikely for two reasons. First, the average ear canal is about 1 1/4 inches long. The typical ear plug is between 1/2 and 3/4 of an inch long. So even if you inserted the entire earplug, it would still not touch the eardrum. Second, the path from the opening of the ear canal to the eardrum is not straight. In fact, it is quite irregular. This prevents you from poking objects into the eardrum.

I work in a dusty, dirty place. Should I worry that our ears will get infected by using earplugs?

Using earplugs will not cause an infection. But use common sense. Have clean hands when using earplugs that need to be rolled or formed with your fingers in order for you to insert them. If this is inconvenient, there are plenty of earplugs that are pre-molded or that have stems so that you can insert them without having to touch the part that goes into the ear canal.

Can you hear warning sounds, such as backup beeps, when wearing hearing protectors?

The fact is that there are fatal injuries because people do not hear warning sounds. However, this is usually because the background noise was too high or because the person had severe hearing loss, not because someone was wearing hearing protectors. Using hearing protectors will bring both the noise and the warning sound down equally. So if the warning sound is audible without the hearing protector, it will usually be audible when wearing the hearing protector. Also, many warning systems can be adjusted or changed so warning signals are easier to detect.

Won't hearing protectors interfere with our ability to hear important sounds our machinery and equipment make?

Hearing protectors will lower the noise level of your equipment; it won’t eliminate it. However, some hearing protectors will reduce certain frequencies more than others; so wearing them can make noises sound different. In cases where it’s important that the sound just be quieter without any other changes, there are hearing protectors that can provide flat attenuation. There are also noise-activated hearing protectors that allow normal sounds to pass through the ear and only “turn-on” when the noise reaches hazardous levels. There are even protectors that professional concert musicians use that can lower the sound level while retaining sound fidelity.

Will we be able to hear each other talk when wearing hearing protectors?

Some people find they can wear hearing protectors and still understand speech. Others will have trouble hearing speech while wearing hearing protectors. Being able to hear what other people say depends on many things: distance from the speaker, ability to see the speaker’s face, general familiarity with the topic, level of background noise, and whether or not one has an existing hearing impairment. In some cases, wearing hearing protectors can make it easier to understand speech. In other instances, people may be using hearing protectors to keep out too much sound. You may need a protector that reduces the sound enough to be safe without reducing the sound too much to hear speech at a comfortably loud level. For those people who work in noise and must communicate, it may also be necessary to use communication headsets. Allow your employees to try different protectors. Some will work better than others at helping them to hear speech, and different protectors may work better for different people.

How long does it take to get used to hearing protectors?

Think about getting a new pair of shoes. Some shoes take no time to get used to. Others – even though they are the right size – can take a while to get used to. Hearing protectors are no different from other safety equipment in terms of getting used to them. But if hearing protectors are the wrong size, or are worn out, they will not be comfortable. Also, workers may need more than one kind of protector at their job. For example, no one would wear golf shoes to go bowling. If hearing protectors are not suitable for the work being done, they probably won’t feel comfortable.

How do I select and use hearing protectors?

Comfort—so you’ll wear them

• Consistency—use them every time, all the time, in hazardous noise
• Cleanliness—keep plugs and hands as clean as possible

How do I insert a foam earplug?

1. Roll the earplug
2. Pull up and away on the top of your ear with the opposite hand to open the ear
3. Hold the earplug after inserting it
4. See instructions “How to wear soft foam earplugs“

How long can someone be in a loud noise before it's hazardous?

The degree of hearing hazard is related to both the level of the noise as well as to the duration of the exposure. But this question is like asking how long can people look at the sun without damaging their eyes. The safest thing to do is to ensure workers always protect their ears by wearing hearing protectors anytime they are around loud noise.

How can I tell if the noise is too loud?

There are two rules: First, if you have to raise your voice to talk to someone who is an arm’s length away, then the noise is likely to be hazardous. Second, if your ears are ringing or sounds seem dull or flat after leaving a noisy place, then you probably were exposed to hazardous noise.

How often should my hearing be tested?

Anyone regularly exposed to hazardous noise should have an annual hearing test. Also, anyone who notices a change in his/her hearing (or who develops tinnitus) should have his or her ears checked. People who have healthy ears and who are not exposed to hazardous noise should get a hearing test every three years.

Since I already have hearing loss and wear a hearing aid, hearing prevention programs don't apply to me, right?

If you have hearing loss, it’s important to protect the hearing that you have left. Loud noises can continue to damage your hearing making it even more difficult to communicate at work and with your family and friends.