Easy-on-the-ears Fourth urged

Firecrackers, noise can do serious damage

July 03, 1999|By Diana K. Sugg | Diana K. Sugg,SUN STAFF

The sound hits the ear with explosive force. The vibrations ride through the ear canal, blow out the ear drum, and when they reach the cells critical to hearing, cells so sensitive that they can detect the sounds of a fly's wings, the noise shears them to pieces.

For all the dangers firecrackers pose this holiday weekend, experts say the most underappreciated risk may be hearing loss.

If set off close enough, a firecracker can permanently damage hearing in an instant. The sound, rather than arriving as vibrations lapping ashore in gentle waves, smashes the ear like a tidal wave.

And nothing can be done to fix it.

"The patients are pretty upset. They say they had no idea firecrackers could do this," said Dr. Lawrence Lustig, an assistant professor of otolaryngology at Johns Hopkins School of Medicine.

Each summer after Fourth of July festivities, Lustig and other physicians typically see some patients complaining of ringing in the ears and other hearing problems caused by M-80 firecrackers, cherry bombs or big fireworks displays.

Some people wind up with a temporary hearing loss, but others, mainly children who are throwing firecrackers at each other when one explodes nearby, suffer irreversible damage.

Health officials rate the sound of firecrackers at 140 decibels, comparable to a jet engine at takeoff or an ambulance siren.

With its marching bands, cannons and stock car races, July Fourth may be the noisiest holiday of the year.

That's why a national coalition of 50 groups is launching a campaign this weekend to convince a reluctant public to save their hearing by protecting their ears.

Too much noise

Americans are losing their hearing at a younger age, and experts believe noise is to blame. In the 1990s, national statistics show that among adult men ages 45-64 years, hearing loss rose by 37 percent; among women, it rose by nine percent. The deficits are cropping up 20 years earlier than expected.

"We're a noisier society than we used to be," said Amy Donahue, chief of the hearing and balance/vestibular sciences branch at the National Institute on Deafness and Other Communication Disorders.

"But you don't have warning signals with noise-induced hearing loss," Donahue said. "If you cut yourself, you bleed, or if you bump against something, you have a bruise. With this, you don't have pain. You don't know you're doing damage to yourself."

No agency tracks hearing loss caused by firecrackers, and authorities say it would be difficult to count, since many aren't reported right away. But according to the national alliance, called WISE EARS, ten million Americans have already suffered permanent hearing loss because of noise.

Another 30 million are exposed to hazardous levels daily, at work and at play, with jet skis, lawn tractors and even in some movie theaters.

Some studies have recently detected a pattern of hearing loss among aerobics instructors, who exercise to blasting music in an enclosed space, which heightens the risk.

But the education campaign must persuade people who dismiss the danger, who think wearing ear plugs is nerdy, or who feel queasy about putting something in their ears.

Earplug education

At Johns Hopkins Center for Hearing and Balance, audiologist Jennifer Anthony sees many middle-aged men who have worked in factories for years. They reject the ear plugs or headphones offered by employers.

"They are just really stubborn, and they don't want to do it," Anthony said. "They said they've lived with it this long, why change now?"

Ear plugs are rated by the decibels they screen out. Lustig, the Hopkins' otolaryngologist, bought a $100 pair for musician's ear plugs that give a truer representation of sound than the cheap ear plugs, which tend to screen out higher frequencies. But even these, available for a few dollars at any drug store, can knock the noise down from a dangerous 100-decibel level to a lower, safer zone.

"There is no reason why people shouldn't have these things at all concerts -- jazz, rock and classical," Lustig said. "But there is a stigma. People want to seem cool, and they don't want to wear their funny yellow-covered ear plugs."

Auditory damage

The ear is a sophisticated system set up to usher sounds into the brain and help interpret them. Noise can injure or ruin this either through a sudden blast or chronic exposure. Three key factors are how long the noise is, how loud it is, and how close it is.

With an unexpected boom, the noise literally rips apart the ear's delicate structures, including the hair cells, which convert the sound waves to electric signals for the brain. Like brain cells, there are a limited number of these, and once destroyed, they are gone forever. In noise exposure that accumulates over time, hair cells are killed off gradually.

Typically, people lose their hearing in the higher-range frequencies first. That means a person often can't distinguish between consonants, losing the key letters that distinguish "bat" from "cat," or "loon" from "moon."

Trying to chat with someone at a cocktail party or in restaurant can be useless. Doctors compare it to talking on a cell phone in a crowded area, where the phone picks up pieces of conversations from several other calls.

Warning signs are ringing in the ears, a feeling of fullness in the ears, or trouble shutting out nearby conversations when talking with someone.

For some reason, people have varying susceptibilities for noise-induced hearing loss, and the condition tends to run in families.

Pub Date: 7/03/99

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