Noise induced hearing loss refers to permanent hearing loss resulting from exposure to levels of sound high enough to cause permanent damage to the ears. The American Speech, Language and Hearing Association estimates that almost 12 percent of children between the ages of 6 and 19 currently suffer from noise induced hearing loss. The main culprit behind that worrisome statistic is the increased use of earbud headphones to listen to iPods, iPads, computers, and other electronic devices. When listening at high volumes for too long, noise induced hearing loss can result.
The Mechanism of Hearing Loss
The outer (visible) ear is designed to deliver sound waves through the ear canal, to the ear drum, and finally into the inner ear. The inner ear, also known as the cochlea, is shaped like a snail shell and contains thousands of tiny hair cells which help transmit sound from the ear to the brain. Exposure to excessive noise damages these hair cells, rendering them unable to transmit sound. Once one of these cells is damaged, it cannot regrow or be repaired. The damage can occur gradually and painlessly, but it is cumulative. The longer a person is exposed to loud noise, the more damage is done, and it is not reversible.
How Much Is Too Much?
Decibels are the unit of measurement for how loud sound is. Normal conversation is around 60 decibels. Loud appliances like hair dryers and lawnmowers are about 90 decibels. Rock concerts and racecar engines can get up to 110 decibels. Firecrackers or guns discharging can be even louder than 140 decibels. Anything at 85 decibels or above can cause damage to your hearing. However, the louder the noise is, the shorter the exposure before damage is done. It would take longer to cause the same level of damage mowing a lawn than it would hearing a rock concert.
It’s tricky to make blanket statements about the noise levels of headphones. Decibel levels vary among different styles and different manufacturers. It is generally true that earbud-style headphones are louder than over-the-ear headphones. One study cited by Medical Xpress measured the decibel levels of standard earbuds to determine how long per day they could be used to listen to an iPod before damage is done. They found that with the iPod at full volume, noise levels were such that listening for more than 5 minutes would cause hearing damage. At 90 percent volume, it would take 18 minutes. At 80 percent volume it is safe to listen for 1.2 hours before risking damage, and at 70 percent it is 4.6 hours. When volume is reduced to 60 percent you would have to listen for more than 18 hour a day to cause damage. Below 50 percent volume it was safe to listen continuously without causing damage.
The best way to avoid hearing damage is to limit or avoid exposure to excessive noise. By keeping headphones at a reasonable level or at least restricting the amount of time they are at higher levels, noise induced hearing loss can be prevented. Wearing ear muffs or ear plugs while mowing the lawn or doing other work involving loud machinery will also protect your hearing (many professions involving loud equipment require ear protection to be worn). Cutting down on how long you expose your ears to loud music now could help you ensure that you’ll still be able to hear those lyrics for years and years to come.