The ancient Greeks had lots of snails and knew exactly what they looked like. When early Greek doctors discovered a spiral-shaped cavity behind the middle ear, they called it a kokhlias, meaning snail.
Today, that part of your ear is called the cochlea (say coke-lee-a). When sound waves pass through its spirals, vibrations cause some 16,000 tiny hairs to send impulses to the brain. Problem is, if the hairs in that snail are destroyed, they're gone forever. They will never regenerate.
Noise damages the ears in two ways. It can strike in an instant and cause acoustic trauma. A blast from a high-powered hunting rifle can rip apart the ear's inner tissues and leave scars that interfere with hearing.
Damage can also develop slowly over decades because of noise-induced hearing loss, or NIHL. Any sound louder than 85 decibels (dB) can be tolerated for only a certain period of time without damage.
To calculate 85 dB, consider the sound of a vacuum cleaner. At a rating of 80 dB, there is virtually no limit on the amount of time you can hear it continuously without damage.
At 90 dB, the rating for most power lawn mowers, you could suffer hearing damage after 8 hours of continuous exposure. Other common sounds, their dB ratings, and time limits for safe exposure are:
Power drill 100 2 hours
Rock concert 120 7.5 minutes
Jackhammer 130 3.8 minutes
Gunshot 140 none
Doctors at the League for the Hard of Hearing in New York City say this is how to preserve hearing:
* Wear earplugs when you are in a noisy environment. If you have to raise your voice to be heard when you are three feet way from someone, you need your earplugs. They reduce noise 20 to 30 dB.
* Give your ears a rest after several hours of noise. Avoid going from one loud event to another.
