University of Virginia Health System

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EVERYDAY ACTIVITIES INCREASE RISK OF NOISE INDUCED HEARING LOSS

With the bloom of spring comes the bustle of lawn maintenance, home repair projects, increased traffic and outdoor concerts.  And with these activities comes the threat of hearing loss. Noise-induced hearing loss affects more than 10 million people and yet is virtually 100 percent preventable. 

Noise-induced hearing loss is categorized as either noise-induced hearing loss (NIHL) or acoustic trauma.  NIHL is caused by prolonged exposure to loud levels of noise that damage the inner ear.  Acoustic trauma is caused by a single, loud noise or explosion that damages the inner ear, and is difficult to prevent because it is usually caused by an unforeseen event. 

“When someone goes to a concert, cuts grass or runs a power saw, they can suffer from NIHL,” said Dr. George Hashisaki, assistant professor of otolaryngology at the University of Virginia Health System.  “Afterwards, if their hearing is muffled or their ears are ringing, they have suffered NIHL.  Even if their hearing comes back to what they perceive as normal, a small part of that hearing loss is permanent.

“If you are mowing grass, working on home repair projects using power saws and loud tools, or at a loud event such as a concert, wear some sort of ear protection, be it earmuffs or earplugs.  It is the type of injury where prevention is the most effective treatment.”     

According to the Occupational Safety and Health Administration (OSHA), noise-induced hearing loss may occur after eight hours of exposure to noise levels of 85 decibels (dB) or higher.  OSHA guidelines limit exposure to 8 hours at noise levels of 90 dB in the workplace. Each five-decibel increase above 90 dB reduces exposure time by half.  These guidelines can be adopted for general use, Hashisaki said. Running a lawnmower at 90 dB should be limited to 8 hours; a tractor at 95 dB to 4 hours; power tools at 100 dB to 2 hours; and earphones at 110 dB should be limited to 30 minutes.

People who are most in jeopardy of losing their hearing are those who use firearms regularly without ear protection or who are in the military and unable to wear hearing protection, such as those on the frontlines, Hashisaki said.  The noise level of gunshots can reach 170 dB and is capable of immediate damage.  Hashisaki recommends wearing both earplugs and earmuffs to protect hearing while target shooting.

Since it may be difficult for individuals to realize they have reduced hearing capacity, Hashisaki also recommends a hearing test every five to six years by an audiologist.  One sign of NIHL is difficulty in understanding conversations. Loss of hearing in the high-pitched frequencies interferes with our ability to understand speech sounds. Noise-induced damage to hearing has the greatest effect in the high frequencies.

According to the National Institute of Health, twenty-eight million Americans have some degree of hearing loss and about one-third can attribute a portion of their hearing loss to excessive noise above 90 dB.  Common causes of NIHL include:  guns, snowmobiles, go-carts, power tools, stereo headphones and household appliances, including vacuum cleaners and garbage disposals.  Once a person has suffered from NIHL, the only treatment option is hearing aids.