Reaction Time Reduced

Loud music in cars could be dangerous: study

Canadian Press
Updated: Sun. Mar. 21 2004 8:02 PM ET

ST. JOHN'S, Nfld. - Much to the horror of teenagers everywhere, a recent study has proven what parents have long suspected - loud noise decreases reaction time and decision-making ability. The study is bad news for decibel-loving drivers, says Dr. David Behm, a professor of human kinetics at Memorial University in Newfoundland. "If it's noisy and you're listening to CBC Radio really loud and you're driving, we would expect that your reaction time and your movement time would be decreased and your ability to concentrate on a complex task would also be decreased," he said.

The study had people perform physical and mental tasks while listening to levels of noise varying from 53 decibels (about the level of background noise in an office) to an industrial-strength 95 decibels (the equivalent of an oil rig). Measuring physical and mental abilities over the course of an hour, researchers found that reaction time decreased at higher noise levels. At office level, it was depressed five per cent. At 95 decibels, the ability to perform physical tasks decreased about 10 per cent. For complex tasks that require decision-making, in this case playing a video game, reaction times decreased an average of 20 per cent at the highest level of noise.

Although it translates into mere fractions of a second, on the road those fractions make a big difference, said Duane Button, who performed the study while a master's student at Memorial. "You have people and vehicles and pedestrians and stop signs and lights all coming at you at one time. You have this noise blasting in your ear. You have your kids behind you," Button said from Winnipeg, where he is pursuing doctoral studies at the University of Manitoba. "If you lose a bit of reaction time then that .035 seconds can be the difference between an accident or not."
On the job, the study proves that loud work environments without the proper ear protection could mean more accidents, Behm said. Workplace regulations limit the amount of exposure to 95-decibel noise to one hour, but the length of exposure to the noise didn't make a difference in the study. The effect was immediate and ongoing. "What we thought was that perhaps over time you'll get what's called accommodation," Behm said. "If you're sitting in your car and you turn on your radio and the traffic around is loud so you turn up the radio a bit more. Then a good song comes up and you turn it up a bit more. You keep on turning the radio up ... The next day you get in the car and the radio is blasting and you wonder how the hell did I have the radio up so high? What happens is your ears accommodate to noise." Your ears may accommodate to noise but it appears your brain doesn't. "Reaction time stayed depressed the whole time," Button said.

But there is some hope for teenaged drivers for whom blasting urban beats are as important as gasoline or turn signals. The study did not look specifically at music. And although parents may consider the latest from 50 Cent worse than a jackhammer, Button leaves room for a lesser reaction. "Noise for me may not be noise for someone else," Button said. So perhaps the driver should always rule the radio, after all.