June 16, 2000 -- The world is a noisy place. Stereo headphones can blast music into both ears at sound levels equal to that of a diesel locomotive. Power tools meant for home use can create levels of noise once heard only by workers in high-risk occupations. Snowmobiles, leaf blowers, and motorcycles add to the din.
It's no wonder that noise-related hearing loss is the second most common form of acquired deafness (aging is in first place). And many experts believe that much of the hearing deficit that comes with increasing age is related to the cumulative effect of noise.
The inability to hear sounds at high frequencies, and the inability to understand speech -- the kind of hearing loss associated with noise -- is becoming such a problem that Peter M. Rabinowitz, MD, MPH, was prompted to review the causes and preventive steps for physicians in a recent issue of the American Family Physicians. "Physicians who stress preventive care should be aware of noise-induced hearing loss, since it is 100% preventable," Rabinowitz tells WebMD.
To help educate patients who come to the doctor for other reasons, Rabinowitz also has written an informational guide that physicians can distribute in their waiting rooms. "How to Prevent Noise-Induced Heart Loss" explains how to tell if noise might be harming your ears. For instance, it says: "If you have to shout when you talk to a coworker who is standing next to you, the noise level at your workplace may be hurting your ears." The "shout test," Rabinowitz says, can be used in any situation to determine if you should be using earplugs or other types of protection.
Noise is harmful because it damages cells within the cochlea, a snail-shaped organ within the ear. These cells have tiny hairlike projections that are stimulated by sound. The stimulation is transferred by nerves to the brain, where it is interpreted as sound. The delicate cells of the cochlea can repair themselves if damaged, but eventually, permanent damage may occur.
"If the ears are overstimulated by, say, [music at] a rock concert, your ears may ring or feel like they have cotton in them for a day or two. The cells may recover. That's called a 'temporary threshold shift,'" Rabinowitz says. "But if that goes on too many times, or is too severe, the [cells] can't recover, and they die. You're born with a certain number of hair cells, and that's all you have."
If you answer "yes" to questions such as: "Do you have difficulty hearing when someone speaks in a whisper?" or "Does a hearing problem cause you difficulty when listening to television or radio?," you may need a professional hearing test. If hearing loss is detected, it can be prevented from getting worse if you stop doing whatever is causing the damage. A physician can help do the detective work and track down what noise exposure is too great or too prolonged or both.
Rabinowitz advises that a doctor should confirm the cause of any hearing loss. "There are other things that can cause hearing loss, such as a growth or certain diseases," says Rabinowitz, an assistant professor of medicine at Yale University School of Medicine in New Haven, Conn.
"Education can come from a lot of venues, but having it come from the personal physician adds credibility and an opportunity to ask questions." says Amy Donahue, PhD, chief of the hearing and balance section of the National Institute on Deafness and Other Communication Disorders.
One source of noise is firearms, and a study by researchers at the University of Wisconsin found that the use of recreational firearms -- guns used for hunting and target shooting -- is linked to hearing loss. Lead researcher Karen J. Cruickshanks, PhD, and study author David M. Nondahl, MS, report in the Archives of Family Medicine that men who engage in these activities are twice as likely to experience hearing loss.
"I was surprised at the number of target shooters who did not wear hearing protection," Nondahl tells WebMD. "I can't imagine firing 50 to 100 rounds in an hour without [it]. The noise is extremely intense." Nondahl is a biostatistician with The Epidemiology of Hearing Loss Study and an associate researcher at the University of Wisconsin Medical School.
Nondahl and his colleagues found in their study of about 1,500 men, between the ages of 43 and 84, that over a third of the target shooters never wore hearing protection while shooting during the past year.
Most hunters (95%) don't wear any protection, either, but the authors point out that hunters need to be able to hear their prey and communicate with their hunting partners. But the authors point out that level-dependent earplugs have been shown to protect the ears while allowing communication.
In the Wisconsin study, both hunters and target shooters had an increased risk of high-frequency hearing loss. And, says Nondahl, the loss was severe in half of the men.
"This study provides further evidence that firearms are a factor in noise-induced hearing loss. Whether you are a hunter or practice shooting at a firing range, you should wear hearing protectors at all times," says Donahue, who reviewed the study for WebMD. "Each exposure [to the intense noise] creates more damage, and the effects are cumulative over time. "
- Noise-related hearing loss is the second most common form of acquired deafness, after aging.
- If you have trouble hearing someone when they speak in a whisper, or difficulty hearing the television or radio, a professional hearing test may be in order.
- Hearing loss can be prevented or slowed by discontinuing whatever activity causes it. One activity that may damage hearing is shooting firearms for sport without wearing ear protection.