From our perspective, a lawn mower, an industrial factory and a nightclub may not have much in common. But as far as our ears are concerned, it's all noise, explains Theodore W. Fetter, MD, a member of the American Academy of Otolaryngology–Head and Neck Surgery.
Though we often associate hearing loss with advancing age, most cases result from exposure to excessive noise.
Any source of loud noise has the potential to damage the structures of the inner ear and cause permanent hearing loss. Noise-induced hearing loss (NIHL) can happen anytime from infancy to old age. It can't be reversed, but it can be prevented.
How it happens
We hear sounds when sound waves enter the ear and travel through the outer and middle ears to the cochlea in the inner ear. This hollow, snail-shell-shaped structure is filled with fluid and has nerve endings called hair cells.
The sound waves disturb the fluid in the cochlea, which stimulates the hair cells. This sends a nerve signal to the brain, which interprets the signal as a sound.
Loud noises create powerful sound waves that can damage the hair cells. Permanent damage may result from a single, powerful noise or repeated exposure to less intense noises.
How serious is it?
NIHL most often causes problems with understanding speech and communicating with others.
People with hearing loss may have to strain to understand conversation, which can lead to withdrawal and loss of self-esteem. As a result, people may begin to avoid social situations altogether. This can lead to isolation and depression. Depending on your job, hearing loss can also make it difficult to work.
What's too loud?
Noise level is measured in decibels (dB). The decibel scale ranges from 0 dB, the quietest noise the human ear can hear, to more than 180 dB, the noise level a rocket produces when it launches.
Sounds at or below 70 dB aren't likely to cause hearing loss under any circumstances, says the National Institute on Deafness and Other Communication Disorders (NIDCD). This includes normal conversation, a sewing machine or a typewriter.
When it comes to louder noises, the picture gets a bit fuzzier. Several factors determine whether a noise will cause permanent hearing loss, according to Dr. Fetter.
These factors include:
- How close you are to the noise source.
- How loud the noise is.
- How long you're exposed to the noise.
Also, some people's ears are more sensitive to noise than others'.
Frequent sources of ear-damaging noise include:
- Loud music (at home or in nightclubs).
- Power lawn mowers.
- Industrial machinery.
- Power tools such as snowblowers, shop tools and chain saws.
- Snowmobiles, personal watercraft and some motorcycles.
Even small bits of exposure to loud noise can eventually add up to permanent damage. That's why you should protect your ears anytime you're exposed to noise that may be too loud.
A good rule of thumb, Dr. Fetter says, is that a noise is too loud if you have to yell or speak loudly to be heard by a person an arm's length away.
If you walk away from a room or activity and your ears are ringing or your hearing is muffled or distorted, you've probably done some damage.
Taking care of your hearing is neither difficult nor expensive, Dr. Fetter says. Avoid loud noises when you can, and if you can't avoid the noise, protect your ears.
Look for earmuffs or earplugs at drug, hardware, music or sporting good stores. An audiologist can make custom plugs that form fit your ears.
When you wear earmuffs or plugs properly, you should be able to tell a difference in the volume of outside noise and your own voice should sound louder and deeper.
Listen to your ears
If you already have hearing loss, a doctor can help you manage it and prevent further hearing loss.
According to the NIDCD, a yes answer to three or more of these questions may mean it's time to see a doctor about your hearing:
- Do you have trouble hearing over the telephone?
- Do you have trouble following a conversation if two or more people are talking at the same time?
- Do people say you turn the TV volume up too high?
- Do you have to strain to understand conversation?
- Do you have trouble hearing if there's background noise?
- Do you often ask people to repeat themselves?
- Do many people you talk to seem to be mumbling?
- Do you misunderstand other people and respond inappropriately?
- Do you have particular trouble understanding the speech of women and children?
- Do people get annoyed because you misunderstand what they say?
Prevention is best
There's no way to treat NIHL. Hearing aids help many people cope with hearing loss, but they can't cure it. Hearing aids for your ears are like glasses for your eyes, Dr. Fetter says. These tools don't improve your eyes or ears. They just help you function with the problem you have.
It is far better to not acquire NIHL in the first place. And that means protecting your ears from loud noises throughout your life.