FRIDAY, Feb. 16, 2007 (HealthDay News) -- Permanent hearing loss will occur in 17 percent of people exposed to airbag deployment in cars sold in the United States, new research suggests.
Dr. G. Richard Price, a consultant at Auditory Hazard Analysis in Charlestown, Md., only looked at cars with front and side airbags sold in the United States, which are required to have larger, more powerful airbags than cars sold in Europe and other parts of the world. Cars with smaller airbags likely pose less of a hearing threat, Price said.
He also found that, contrary to widespread belief, car occupants are more likely to suffer hearing damage when the windows are rolled down.
Experts had believed that having the windows rolled up was more dangerous to hearing, because there'd be more pressure inside the car. Price said he found that the higher pressure caused by airbag deployment in cars with rolled up windows actually prevents greater damage to the ear.
The increased pressure with the windows rolled up actually causes a displacement in the middle ear that stiffens the stapes, which is a small bone outside the inner ear, according to Price. The stiffening of the stapes limits transmission of energy to the inner ear, where hearing damage occurs.
In fact, experiments showed that hearing damage is further reduced when a passenger cabin is completely sealed, resulting in even higher pressure when airbags deploy, Price said.
In a presentation scheduled to be made Friday in Savannah, Ga., at the National Hearing Conservation Association's (NHCA) annual meeting, Price is also expected to discuss the danger to hearing posed by everyday "impulse" noises -- brief bursts of sound such as a hammer hitting a nail or even the sound of a baby's rattle.
Price's work offers a glimpse at an aspect of new technologies people rarely think about, said NHCA Director of Education Brian Fligor.
"We often consider only the benefits of safety technology, rather than the unfortunate potential side effects. This type of study highlights how common everyday occurrences present a very real hazard to our hearing," Fligor said in a prepared statement.
The American Academy of Otolaryngology-Head and Neck Surgery has more about noise and hearing protection.