Researchers at the University of Bath and Bath Spa University in England say the distinctive roar of a Harley's engine is loud, but studies have revealed the biggest source of noise for motorcyclists is actually generated by air whooshing over the riders' helmets. Even at legal speeds, the sound can exceed safe levels, the researchers say.
The researchers placed motorcycles helmets atop mannequin heads, mounted them in a wind tunnel and turned on the fans. By placing microphones at various locations around the helmet and at the mannequin's ear, the researchers found that an area underneath the helmet and near the chin bar is a significant source of the noise that reaches riders' sensitive eardrums.
The team also investigated how helmet angle and wind speed affected the loudness.
The study, Aeroacoustic Sources of Motorcycle Helmet Noise, is accepted for publication in the Journal of the Acoustical Society of America.
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