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Loud headphones are making us prematurely deaf

(Paul Hudson)

Complaining about kids blasting loud music and wearing headphones is the epitome of crankiness.

But loud music and headphones — along with the other sources of loud noise in modern society — are slowly driving us deaf.

While age-related hearing loss has plagued humans for generations (ever since our lifespans grew long enough to be an issue), noise-induced hearing loss is a growing problem.

Somewhere between 10 and 26 million Americans suffer from it, and many of them are teenagers or kids: some researchers estimate that as many as 12.5 percent of those between 6 and 19 years old already have degraded hearing due to excessive noise exposure.

"For many young people, the hearing loss may not have any immediate impact, and it'll be shrugged off," says Robert V. Harrison, an audiologist at the University of Toronto who studies youth hearing loss. "However, in the years to come, there will be consequences, especially when this damage is combined with age-related hearing loss."

Here's a look at how loud noises damage our ability to hear — what you can do to preserve your ears.

How hearing loss happens

To understand hearing loss, it helps to understand hearing.

Sounds are waves of vibrations that travel through the air. When they enter your ear, they hit your eardrum and cause it to vibrate. These vibrations are then passed along three tiny bones (the malleus, incus, and stapes — the smallest bones in the human body), which ultimately cause fluid in a spiral-shaped cavity called the cochlea to move accordingly.

inner ear

(Dan Pickard)

Inside the cochlea are millions of tiny hairs topped with microscopic structures called stereocilia. When they're moved back and forth by the fluid, they send corresponding electrical impulses down the hair cells based on the movement's frequency. The impulses are then picked up by the auditory nerve and carried into the brain, where they're interpreted as sound.

It's remarkable: a chain of events that allows creatures with electrical thought processes to communicate by sending vibrations through air.

But it's also a fragile process. "The motion of these stereocilia and the delicate connections between structures are susceptible to mechanical damage," Harrison says. Very loud noises (vibrations that move through the air at higher pressures) can damage these tiny structures and the attachments between them over time, and the stereocilia cells in particular can't grow back. Having fewer of them makes you less sensitive to smaller vibrations — which means that you're less capable of hearing softer sounds, like the subtle ones that make up human speech.

Noise exposure can also degrade your ability to hear in other ways. Harrison notes evidence that excessively loud noises can disrupt the processes of some of the specialized cells in the cochlea, causing buildup of metabolic byproducts. It might also disrupt the blood supply to some of these cells over time, causing oxygen depravation.

Regardless of the mechanism, he and other researchers observe a clear pattern: hearing loss is a function of both the volume of the loud noises you hear, but also the length of time you hear them for. This means that standing next to a jackhammer (which produces a sound of about 120 decibels) for less than a minute can damage your hearing, but so can riding a gas-powered lawn mower (about 90 decibels) for a couple of hours.

Generally, noise-induced hearing loss begins with losing the ability to clearly hear relatively high tones — those with frequencies of between 2000 and 4000 hertz, which roughly correspond to the upper end of the human voice register. Oftentimes, someone with premature hearing loss can still tell that someone else is speaking, but they'll have a tougher time making out the words, especially in a loud place like a crowded bar or party. Over time, the problem gets worse and worse — especially when combined with the natural age-related hearing loss that strikes most people.

Society's noise problem

headphones 2

(Sascha Kohlmann)

For most of human history, there were few sounds — perhaps a crack of thunder, or the gush of a waterfall, or the bark of a wild animal — that were loud enough to damage our hearing. That changed with the invention of heavy machinery and other electrically-powered devices.

Today, the majority of noises louder than 85 decibels — the threshold recognized to cause damage over time — are heard by people in industrial, military, or other work settings. In the US, at least, the Occupational Safety & Health Administration regulates noise exposure for workers, requiring employers to provide ear protection and take other measures to minimize damage. It's not perfect, but most people who work with loud machinery everyday are aware of the risks and have some level of protection.

The bigger problem, Harrison says, is casual noise exposure from things like concerts, sporting events, and most commonly, your own headphones plugged into a device that's turned all the way up. "These are all poorly regulated or totally unregulated," he says. "When it comes to personal entertainment devices — like phones or MP3 players — each person can make his or her own decision about exposure levels, and children and teens often don't choose wisely."

Being at a loud concert or bar — which can easily produce 115 decibels of noise — can cause hearing damage in as little as 15 minutes. But a standard pair of earbuds can also produce 100 decibels of sound (which can cause hearing damage after about 2 hours of exposure) and some headphones can produce up to 110 decibels (which can cause damage in 30-45 minutes).

noise chart

(American Academy of Audiology)

There isn't great data on exactly how many people suffer from noise-induced hearing loss, but the number of Americans is at least in the tens of millions, and many researchers think the problem is escalating due to all the kids and teenagers wearing headphones with the volume turned all the way up.

Research indicates that young people, on average, listen to three hours of music per day, and one study found that 17 percent of teenagers sampled used headphones at levels that increase their risk of hearing loss over time. When asked why, many said they'd assumed the devices and headphones were designed so they couldn't be turned up beyond safe levels. This is not the case, and Apple has actually been sued over it — and though it won the case, it now warns users of its products to "listen responsibly."

Perhaps most concerning is the possibility, among young people, that noise-induced hearing loss could fuel itself: when someone's hearing is damaged, especially at a young age, they might listen to music at a higher level in order to hear it better, thereby accelerating further damage. Because it happens gradually, they probably wouldn't have any idea.

How to save your ears

ear

(Shutterstock.com)

The main thing is exposure: the more noise you're exposed to — both in terms of volume and duration — the more damage will occur. Anything over 85 decibels is bad, but 100 or 110 is much, much worse.

Most professional musicians and people who work with loud machinery already know this. But people who are occasionally exposed to loud noises at events or during recreational activities probably don't think about it.

If you're going to a concert, sporting event, or bar that you expect to be loud (and don't plan on doing much talking), consider bringing earplugs. You'll still be able to hear the show, and there are some transparent types of earplugs that won't make you look quite as much like an old fogey.

When it comes to headphones, audiologists recommend something called the "80-90 rule": listening at no more than 80 percent of a device's volume at any given time, and taking a rest from music every 90 minutes, to give your ears a rest and prevent them from becoming desensitized to louder sounds. Some devices (including iPhones) allow you to set a volume maximum to ensure you don't accidentally go over this.

Wearing earplugs to concerts and capping the volume of your music is one guaranteed way to seem old and responsibly lame. But if you want to preserve your hearing for as long as possible, it's worth it.

"The thing is, there's no cure for hearing loss," Harrison says. "Prevention is the word."