Experts recommend avoiding sounds louder than 70 decibels (about the volume of a vacuum cleaner) for long periods of time. Sounds louder than 85 decibels (about as loud as a lawnmower) can irreversibly damage your ears after prolonged exposure.
And a surprising number of sounds we encounter in our daily lives exceed this threshold: The average noise level at a movie theater is between 74 and 104 decibels. The maximum volume for most audio devices (MP3 players, phones) clocks in between 94 and 110 decibels.
If you live in an urban area, where sirens (between 110 and 129 decibels) and motorcycle engines (between 80 and 100 decibels) are commonplace, you are at a higher risk for noise-induced hearing loss, or NIHL, than people who live in more residential regions.
According to the Centers for Disease Control and Prevention, approximately 12.5% of children and adolescents between the 6 and 19, and 17% of adults between 20 and 69, have suffered permanent damage to their hearing from excessive exposure to noise.
The fact more people have been using headphones in recent years has made NIHL more prevalent in the U.S.
“The World Health Organization has estimated that by 2050 there will be a billion people with a disabling hearing loss,” according to a 2019 Science Friday article. “Two-thirds of Americans who are seventy or older have lost some hearing, according to various estimates.”
How hearing works
To understand how NIHL manifests, it’s important to understand how hearing actually works.
Our ears can be compartmentalized into three parts. The outer ear absorbs sound waves and directs them to the ear canal, where the sound is amplified. When these sound waves reach our eardrum, they cause it to vibrate before they travel deeper into our ear canal. The middle ear is responsible for equalizing the pressure of the air outside the ear and the air within the ear. The inner ear is filled with tiny hairs and fluid that move in response to sound waves. As that fluid moves, 25,000 nerve endings translate the vibrations into electrical impulses that then travel along the auditory nerve to the brain, which translates them into the music, conversation, and noise we hear.
Excessively loud sounds, however, disturb the inner ear by bending the hairs that line the inner ear, which causes ringing and temporary loss of hearing.
“Researchers have found that people who are exposed over long periods of time to noise levels at 85 dBA or higher are at a much greater risk for hearing loss,” according to a National Institutes of Health website. “That’s why some workers are required to wear hearing protectors, such as earplugs or earmuffs, while they are on the job.”
Industries that put workers at the greatest risk for hearing loss include the military, mining, manufacturing, agriculture, transportation, carpentry, and plumbing.
Temporary hearing loss or permanent?
Temporary hearing loss caused by exposure to loud noises usually lasts between 24 and 72 hours. NIHL, however, is permanent. Neither condition is preceded by painful symptoms.
The most common characteristics of NIHL include feelings of pressure or fullness in the ears, speech that seems to be muffled or far away, and a ringing sound in the ears that you notice when you are in quiet places.
How to protect yourself against permanent hearing loss
Diet and exercise play a huge role in NIHL prevention. Obesity, for instance, can disrupt blood flow to areas of the brain important for hearing. Excessive smoking and drinking can similarly disrupt mechanisms within the inner ear. And routine exercise can improve blood flow, which can, in turn, reduce the likelihood of developing NIHL, even where it’s loud.
“Whether noise harms your hearing depends on the loudness, the pitch, and the length of time you are exposed to the noise,” according to the American Academy of Family Physicians. “The louder the sound, the shorter the exposure can be before damage occurs. For example, eight hours of exposure to 85-[decibel] noise on a daily basis can begin to damage a person’s ears over time.