NIHL can present after exposure to sudden, loud sounds or from a loud sound experienced over a prolonged period of time. The distance from the sound source also matters.

What to protect

Loud sound damages sensitive structures in the inner ear known as hair cells, which are located in the cochlea. Hair cells are so named because of their long, thin shape. These cells convert sounds into electrical impulses that travel to the brain to be interpreted. But once these hair cells are damaged, the loss of hearing becomes permanent.

The rule of thumb for safe noise exposure is no more than 85 decibels for a maximum of eight continuous hours. The decibel, or dB, is a unit to measure sound intensity, and 85 dB is roughly equivalent to the sound of heavy city traffic. By comparison, normal conversation is about 60 dB, and a motorcycle 120 dB.

Environmental risk

The louder the volume, the shorter the duration for safe listening. The “daily noise dose” for 100 dB—a rock concert or a nightclub—is only 15 minutes, according to the National Institute of Occupational Safety and Health. But how many of us stay at a rock concert for only 15 minutes? Even movie theaters and school dance parties can pose a risk.

"A 2010 Journal of the American Medical Association study found that documented hearing loss among adolescents jumped by a third over about a dozen years."

If you are in an environment where you have to shout to be heard, it’s probably too loud. To be sure you’re keeping your ears safe, use a decibel meter—there are many available as smartphone apps—and then follow these steps: walk, block and turn. Walk away from the sound source, block your ears using earplugs and turn down the volume.

Budding concern

Because ear buds do not effectively block ambient noise, you may find yourself cranking up the music from your personal music player so you can hear it over other sounds, such as people talking in the subway, other music at the gym or traffic.

This has led to the World Health Organization’s recommendation to use ear buds with personal audio devices for no more than one hour a day, based on a review of research showing that ear bud volume averages 94 dB. The WHO estimates that 1.1 billion—yes, billion—young adults worldwide are at risk of hearing loss due to unsafe listening habits.

A 2010 Journal of the American Medical Association study found that documented hearing loss among adolescents jumped by a third over about a dozen years. The study estimates that 1 in 5, or 20 percent, of U.S. teenagers are currently affected by hearing loss. Hearing loss is already the third most common chronic condition among older Americans.

Rest your ears. If you can’t cut the volume, walk, block and turn.