The unit used to measure sound is a decibel: While a whisper may be 30 decibels, and normal conversation 60 decibels, a hair dryer may be 90 decibels and a leaf blower 110 decibels. An increase of 10 on the decibel scale means the sound is ten times more powerful.
Dr. Beyer cautions that, over time, prolonged unprotected exposure to noise levels above 85 decibels can cause permanent hearing loss by damaging the sensitive cells in the inner ear that convert sound energy into electrical signals that travel to the brain.
The NIDCD warns that regular exposure of more than one minute to 110 decibels risks permanent hearing loss and recommends no more than 15 minutes of unprotected exposure to 100 decibels.
The Sight and Hearing Association estimates that unprotected hearing can be damaged in 7.5 minutes at a rock concert (120 decibels), four hours on a motorcycle or when using a power saw (95 decibels), 15 minutes at a stadium football game (115 decibels) and eight hours in truck traffic (90 decibels).
In the workplace, the National Institute for Occupational Safety and Health (NIOSH) has determined that the safe limit for noise exposure at 85 decibels is eight hours a day. However, each three decibel increase in noise cuts the safe exposure time in half (four hours at 88 decibels, and two hours at 91 decibels).
If there are symptoms of hearing loss, including sounds that appear distorted or muffled, a ringing in the ears, a feeling of fullness in the ears and difficulty understanding speech, a hearing test is essential, says Dr. Beyer.
Which noises to be wary of? Dr. Beyer says she agrees with the NIDCD’s advice to avoid noises that are “too loud” and “too close” or that last “too long.”
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