Noise and Hearing Loss

Exposure to loud noise is the most common cause of hearing loss. Noise-induced hearing loss (NIHL) can be prevented but not reversed.

How does noise affect hearing?

Sounds entering your ear pass through your eardrum and into the inner ear. Tiny hairs in the inner ear change the sound waves into nerve impulses. Hearing nerves carry these impulses to the brain, where they are interpreted as sound. Different sounds affect different parts of the ear. This allows the brain to distinguish one sound from another, such as vowels from consonants.

You are born with about 30,000 hair cells in the inner ear and that's all you get. If some of these cells are destroyed, the cells are not replaced. The hairs in the inner ear are very sensitive and fragile. They can be destroyed by noise in 2 ways.

• A very loud and sudden noise can immediately destroy the hairs in much the same way a hurricane knocks down trees.
• More often, the hairs are hurt by stress from chronic noise. Overstimulation by ongoing noise creates chemicals that damage the hairs.

What kinds of sounds cause hearing loss?

Sudden very loud sounds such as explosions, gunfire, or firecrackers sometimes cause immediate damage to the hair cells and permanent hearing loss. Exposure to loud or moderate noise for long periods of time also hurts these hair cells. Everyday devices such as power tools, chain saws, blow dryers, or personal stereos can damage hearing in this way.

The loudness of sound is measured in decibels. For example, normal conversation is approximately 60 decibels, the humming of a refrigerator is 40 decibels, and city traffic noise can be 80 decibels. Noise levels greater than 80 decibels can be hazardous. Motorcycles, firecrackers, and firearms can produce sounds from 120 to 140 decibels and cause hearing loss. Sounds that are less than 80 decibels, even after long exposure, are unlikely to cause hearing loss.

Here are some sounds that can cause hearing loss after continued exposure:

• At home: The noises in and around our homes can damage our ears. Blenders, hair dryers, electric mixers, garbage disposals, vacuum cleaners, whistling kettles, and coffee grinders can all create noise up to 90 decibels. Lawn mowers, leaf blowers, chain saws and other power tools can be over 100 decibels. Personal stereos with headphones and the volume turned all the way up have been measured at up to 112 decibels.
• At work: Millions of Americans are exposed to harmful noise levels regularly at work. Anyone who works around heavy machinery, on busy city streets, or wherever loud music is played is at risk. Musicians and people who work in rock music venues aren't the only ones who should worry. Many classical musicians also have job-related hearing loss.
• Having fun: Noise levels at concerts, where music is often louder than 120 decibels, can damage your ears in 10 seconds. Arena and stadium sporting events and car racing can be just as loud. Gunshots, at 160 decibels or more, literally tear the inner ear.
• Traveling: Subways, airplanes, traffic on city streets, and other transit noises are often at an ear-damaging level. Riding a motorcycle without protection can easily cause hearing loss.

What are the symptoms of hearing loss?

For most people, 120 decibels hurts. If, after exposure to noise, you have a buzzing, ringing, crackling, or roaring sound in your ears, or other people's speech sounds muffled, then the noise has damaged your hearing. Feelings of ear fullness or pressure may also happen after you hear a loud noise. These symptoms may start to go away after a few minutes or they may last a couple of days or longer. The sounds in your ear, called tinnitus, may continue constantly or occasionally throughout your life.

As noise exposure is repeated, more cells are damaged and the hearing loss becomes permanent. The loss may go unnoticed for a while because it causes very few obvious symptoms. The first noticeable symptom is the loss of the ability to hear higher pitched sounds, such as birds singing. Sounds may become distorted or muffled and it may be hard for you to understand speech.

Can exposure to noise have other health effects on people?

Besides hurting your hearing, noise can affect your body in other ways.

• High blood pressure: Studies have found that people who live near a noisy airport, work in a noisy environment, or hear over 55 decibels of city traffic noise at night are at higher risk of high blood pressure.
• Trouble sleeping: Noise can make it tough to sleep.
• Emotional effects: The stress caused by noise can make mental health problems, such as depression and anxiety, worse. It can make anyone more irritable.
• Poor school or work performance: Children in school and workers on the job do not perform as well in a noisy environment.
• Headaches: Noise can trigger headaches in some people.

How is hearing loss diagnosed?

Hearing loss is detected with a hearing test.

How is hearing loss from noise treated?

Once the ear's tiny hairs are destroyed, they cannot be repaired. If you have a hearing loss from too much loud noise, the best thing you can do is to protect your ears from further damage by avoiding noise whenever possible. If your hearing loss is significant, hearing aids can often help you hear better.

How can I prevent hearing loss from noise?

Noise-induced hearing loss can be prevented with proper precautions:

• Be aware of the level of sound in your home. Turn down the TV, music, and radio volume to the lowest level at which you can hear, and turn them off when you are not actively using them. When you shop for a new appliance, such as a dishwasher or air conditioner, ask about the noise levels of different models.
• If you need to raise your voice above the noise in a room to be heard by someone an arm's length away, you should leave the area. The room's noise level is probably too loud to be safe for a long period of time. This is also true for headsets. If someone else can hear the music coming from your headset, it is probably too loud and the volume should be lowered. Consider using a personal stereo that has an 85-decibel automatic volume limiter.
• Use ear protectors when you are in a loud environment. The devices can range from simple foam earplugs that you can buy at the grocery store to custom earplugs molded to fit your ear. Custom plugs may be worthwhile for people who spend a lot of time in noisy places. Earmuffs that look like big headphones also work well.
• Most earplugs are made to block out high frequencies more than low ones because high-pitched sound is more damaging. If your main exposure is to music and you want to be able to hear all frequencies, consider getting special high-fidelity earplugs designed for musicians. These special earplugs bring the volume down without distorting the sound. To find them check a music store or ask a hearing healthcare provider.
• If you live in a noisy area, try to make your bedroom as quiet as possible. Consider using earplugs or cool your room with an air conditioner or fans instead of open windows.
• Make sure your car's muffler and exhaust system are in good repair.
• The government requires employers to provide hearing protection for employees in noisy work areas. They must also monitor the noise, provide hearing tests, and train employees about noise protection.

When should I see a healthcare provider about my hearing?

See your provider if:

• Spoken words are hard to understand.
• Another person's speech sounds slurred or mumbled, especially if it gets worse when there is background noise.
• Certain sounds are overly annoying or loud.
• You hear hissing or ringing in the background.
• TV shows, concerts, or parties are less enjoyable because you can't hear much.