UF audiologists sound alarm for awareness of motorcycle noise risk

September 1, 2004

GAINESVILLE, Fla. — When the band Steppenwolf sang of heavy metal thunder in “Born to be Wild,” their classic ode to the freewheeling biker lifestyle, they equated rocking out to the new electric music of their time with the ear-pounding experience of riding a motorcycle. The notion that loud music can damage hearing is common knowledge, but the noise produced by motorcycles can pose similar risk to riders, University of Florida hearing experts caution.

In an informal survey of 33 motorcycles, UF audiologists at the College of Public Health and Health Professions have found nearly half produced sounds above 100 decibels when throttled up — equivalent in intensity to a loud rock concert or a chainsaw. The survey is part of an ongoing effort aimed at identifying recreational activities that may pose a risk to hearing, including noise levels experienced by motorcyclists, the hearing specialists said. Because the sample was small and not representative of all makes and models and those with exhaust systems modified to make them louder, formal research is needed to measure noise levels under typical riding conditions and to determine whether these early survey findings can be generalized to a larger number of bikes, they added.

The National Institute for Occupational Safety and Health cautions that exposure to noise at 100 decibels is safe for only 15 minutes. Permanent hearing loss can occur with prolonged exposure to any noise measuring 85 decibels or above.

“Almost all of the motorcycles we tested reached action-level noise, which in the workplace would require ear protection,” said Joy Colle, one of the study’s researchers. “The loudest bike we tested measured 119 decibels with the engine revved, and the recommended exposure time at that level is only 11 seconds.

More than 5 million Americans are registered motorcycle owners, according to the U.S. Department of Transportation. Of the 28 million Americans who have some degree of hearing loss, about one-third can attribute their hearing loss to excessive noise exposure.

In addition to sound levels, the UF hearing experts are noting the make, model, engine size, year manufactured and any modifications to the engine and exhaust systems of each motorcycle. They will in time develop an online database to provide motorcyclists with bike-specific data on noise exposure so riders can make informed decisions about hearing protection.

“At this time, if consumers were to try to find a measure of how loud their motorcycle is, they’d find misinformation,” Colle said. “An Internet search for motorcycle noise levels will yield a 20- to 25-decibel range, with the interested motorcyclist coming away with no useful information. That’s not good enough.”

There is a wealth of data about the effects of noise on hearing in the workplace, Colle said, but relatively little attention has been paid to recreational noise exposure. Motorcyclists, motorboaters, hunters and others should apply the same standards required in the workplace to their recreation activities.

In the UF survey, noise levels were tested at riders’ ear levels from stationary motorcycles when idle and throttled up. Formal research should include measurement of noise levels when the motorcycles are driven at cruising speeds to account for the effects of wind noise, Colle said.

Although noise-induced hearing loss is permanent, it is entirely preventable, Colle said. Motorcyclists should limit the amount of exposure they have to high-decibel levels, and although motorcycle helmets don’t provide any significant protection against noise, inexpensive foam earplugs, available at drug stores, can reduce sound levels by 20 decibels to 25 decibels.

Riders should pay attention to the warning signs of noise-induced hearing loss: a ringing sound in the ears immediately after exposure, and hearing voices and other sounds as muffled.

“These new data about the sound levels to which motorcyclists are exposed will help audiologists and others who work in hearing conservation advise their clients about healthy choices when it comes to how long to ride and when to wear hearing protection,” said Ted Madison, president of the National Hearing Conservation Association. “Consumers may also benefit directly if they have better information about the sound levels created by motorcycles when they go to buy or modify their bikes.”