Theyre all the rage. Loud boom carscars with powerful sound systems that seem to pulse in rhythm to the music within. You can hear them coming down the street in your neighborhood, in front of you at the stoplight or passing you on the highway. But are they really dangerous to hearing? The answer might surprise you.
The car that won the Mankato decibel drag race (see side text) in July roared in at 132.2 dBa sound level similar to a jet engine take-off. At this level, hearing loss for the driver may be instantaneous. On the flip side, a 1992 study compiled by Ramsey & Simmons concluded the average car owner with a stereo cranked at 108 dB may be safe from any risk of noise-induced hearing loss because the amount of time they listen is short.
It is both these factorsdecibels and durationthat cause noise-induced hearing loss, perhaps the most common recreational hazard and a hazard that is completely preventable.
How It Works
In each ear is the cochlea, a coiled, liquid-filled organ that houses microscopic hair cells. These hair cells are stimulated as sound vibrations move down the cochlea. The hair cells help to transform the vibrations into impulses that are sent to the brain. If the sound is loud enough, the hair cells are damaged and/or die off, never able to regenerate. Thus, a hearing loss is born.
Unfortunately, noise-induced hearing loss is painless, so most people dont realize theyre doing any damage, says Ann Napp, an audiologist and advisor for the Sight & Hearing Assn., St. Paul, MN. The feeling that sound is muffled and that ears are ringing are signs of noise damage.
With noise-induced hearing loss, a person loses the ability to hear various sounds that form wordssuch as f, sh, th, t and k. For instance, the word thumb could sound like the word dumb. This can result in miscommunication, frustration and eventual social isolation.
Noise can cause permanent hearing loss at continual exposures of 85 dB or higher for an eight-hour period. Every 5 dB increase represents a doubling of sound intensity. So, for example, four hours of noise exposure at 90 dB is considered to provide the same noise dose as eight hours at 85 dB; a single gunshot, which is approximately 140-170 dB, has the same sound energy as 40 hours of exposure to 90 dB.
So, without taking a noise-level meter with you on the road, how can you protect yourself (and your kids) from hearing loss? Some suggestions:
Check out the noise ordinance where you live. Many ordinances stipulate that drivers will be fined for amplified music that can be heard 50 feet from the vehicle.
Wear earplugs in noisy situations and/or get your kids some earplugs. If youve ever walked away from a concert with your ears ringing, youve experienced a temporary hearing loss and a situation in which the noise levels were excessive. Next time youre around loud music, try wearing earplugs. Youll still be able to hear the music, and youll still be able to enjoy it again when youre older!
Julee Sylvester is PR/marketing director for the Sight & Hearing Assn. The author and HR give permission to reproduce/distribute this article. Correspondence: Julee Sylvester, Sight & Hearing Assn., 674 Transfer Rd., St. Paul, MN 55114; website: www.sightandhearing.org