Convertibles Hazardous to Your Hearing?

Convertible lovers who take to the open road with the top
down may be risking hearing damage, according to a new study out of the
U.K.

"If you are exposed for long periods above 85 decibels [of sound], you have
the potential for hearing loss ," says Philip
Michael, MD, an ear-nose-throat surgeon at Worcestershire Royal Hospital in
Worcestershire, U.K., and the study's lead author. In his study, he found that
the noise level with the top down was higher than 85 decibels. "The maximum
noise was at 70 miles per hour and that was 89 decibels. It has the potential
for causing long-term hearing loss.''

To put those decibel levels in context, a normal conversation is about 60
decibels; a rock concert is about 115 decibels.

Michael is slated to present the study -- which was funded by the
Worcestershire Royal Hospital --  at the American Academy of
Otolaryngology-Head and Neck Surgery annual meeting in San Diego.




Testing Noise Exposure



Previous research done by others about motorcyclists' noise exposure,
coupled with his own love of convertibles, prompted the study, Michael tells
WebMD. Motorcycle riders tend to wear earplugs, he finds.

But the topic of noise exposure to convertible drivers has not been studied
much, he says. So Michael solicited convertible-driving friends who donated six
cars. Another car  -- a Morgan plus 4 Roadster -- was borrowed from the
car company. Then Michael and his co-researchers measured the noise
exposure to a single driver driving seven different convertibles at 50, 60, and
70 miles per hour.

The cars tested were:


  • Toyota MR2

  • Mazda Miata MX5

  • Audi A4 Cabriolet

  • Morgan plus 4 Roadster

  • Porsche 997 Carrera

  • Aston Martin V-8 Vantage

  • Bentley convertible


"We measured the nose by the driver's ear,'' Michael says. Noise by the
driver's right ear -- the roadside ear, in the U.K. -- was measured for one
minute with a sound level meter as the cars were driven at 50, 60, and 70 mph
with the windows lowered and the top down. They also measured the noise
exposure with the windows raised but the top still down when the cars were
driven at 70 miles per hour.

When driven at 70 mph, the noise averaged 89 decibels, Michael found, with
not much difference among the cars, which ranged from moderately priced to
extravagantly priced. ''The car price didn't matter," he says.

The size of the sample was too small to perform statistical analysis,
Michael notes, but he did find a general trend toward increased, although
minimal, noise exposure with speed.




Noise Reduction Remedies



Putting up the windows -- never mind how geeky some feel that looks -- can
cut noise exposure, Michael says. "If you have the top down and put the windows
up, it drops the average to 84 decibels'' for five of the seven cars, he
says.

Putting up the wind guard on the car may reduce noise, too, Michael says.
Earplugs would help, too, he says.

Another idea is to carefully choose your top-down driving location. ''Mainly
the problem is with highway driving," he says, as that is a higher-speed
environment but also often has heavier traffic than city streets or rural
roads, which adds to the noise of the wind and the car noise.




Second Opinion



Two audiologists who reviewed the study results for WebMD call the research
interesting and say it couldn't hurt for convertible drivers to exercise some
caution for their hearing health.

So do the study results suggest there is reason for concern? Yes, says
Alison Grimes, the head of the audiology clinic at the University of California
Los Angeles Medical Center and assistant clinical professor of head and neck
surgery at the David Geffen School of Medicine at UCLA. "I would qualify that
by saying if you drive eight hours a day, seven days a week yu have a much
greater concern than if you drive two hours on a Sunday afternoon."

Rolling up the windows, as Michael suggested, is an option, Grimes says.
"Anything you can do to put up a barrier between you and the sound."

The research, she says, "is sort of a reminder that noise comes from sources
we don't even think about."

Driving your convertible with the top down, she says, "is a little bit like
eating unhealthy food. You can do it occasionally, but don't go overboard.
There are unintended consequences you don't want to deal with.''

"I think people should be cautious," says Debbie Abel, an audiologist in
Poway, Calif., and director of reimbursement for the American Academy of
Audiology. She says she has noticed more drivers putting the convertible top
down and the windows up.

If drivers are considering earplugs, Abel suggests they first check with
their state's motor vehicle department to find out whether they are permitted
by law.



By Kathleen Doheny
Reviewed by Louise Chang
By Kathleen Doheny
Reviewed by Louise Chang
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