American's new affection for portable sound may be exacting a painful price, say hearing specialists. Cordless telephones and personal stereos are the major culprits.
"Most cordless telephones have excessively loud ringers located in the earpiece that continue to ring until the user manually switches the phone to talk-mode," says George Singleton, an ear, nose and throat surgeon at the University of Florida's College of Medicine in Gainesville. "Many people are forgetting to do that, and it's costing them their sense of hearing."
For some people, the loud blast of the electronic ringer causes a permanent hearing loss in the mid-frequency range -- the sound level at which a listener distinguishes word vowels -- says Singleton who has examined more than 35 patients suffering from this kind of problem in the last two years.
Elderly persons, or those with pre-existing hearing loss seem particularly vulnerable, and the number of complaints nationwide, as tallied by the American Academy of Otolaryngology-Head and Neck Surgery Inc., Singleton says, is "increasing like crazy."
More than 120 cordless phone users have complained to the Food and Drug Administration's Center for Devices and Radiologic Health about the hearing damaging effects of the cordless phones -- most within the last year.
In some cases, the damage to their hearing is severe, says FDA spokeswoman Wendy Johnson. The FDA has not taken any action to regulate the phones.
As a result, some manufacturers have designed new models, she says, that either have the ringer in a different part of the headset or have a bell that grows softer with each successive ring.
Chronic exposure to less intense sound -- like a personal stereo cranked up too high -- can prove just as harmful to the inner ear.
"If it's loud enough and lasts long enough," says the Academy's spokesperson Moira DeWilde, "any noise can damage your hearing."
A volume setting of 8 on a 1-to-10 scale produces sound louder than 115 decibels -- greater than the noise exposure the Occupational Safety and Health Administration permits unprotected workers to face, according to studies by a research team led by Arnold E. Katz of Tufts-New England Medical Center in Boston.
In a recent study at the University of Iowa, researcher Phillip Lee and co-workers handed 16 healthy volunteers cassette radios with earphones and asked them to listen to three hours of "rock" or "fusion" music at their "usual preferred maximal listening level." When they compared the hearing sensitivity of each listener before and after the sound session, the scientists found a significant decrease in the ability to detect sound of a given frequency in six of the sixteen volunteers.
As a practical guideline, DeWilde tells parents, "if they can hear the music from headphones on their child's head, it's probably too loud."
Although individuals differ in their sensitivity to sound, as a general rule, noise may damage your hearing, says the Academy, if:
*You have to shout over it to make yourself heard.
*It hurts your ears or makes them ring.
*You are slightly deaf for several hours after exposure.