New studies published in The Journal Of The Acoustical Society Of America warn that if helmets can protect your brain they can also largely contribute to hearing loss.
Results show that the biggest and most dangerous source of noise is not the roar of your engine, but your helmet acting as a special air filter attenuating noise in the region above 500 Hz and amplifying noise in the regions below 500 Hz. Even at legal speeds, the sound of air rushing in areas underneath the helmet and near the chin bar can exceed safe levels.
For demonstration purpose, scientists placed motorcycles helmets atop mannequin heads, mounted them in a wind tunnel, and turned on the fans. By placing microphones at different locations around the helmet and at the mannequin’s ear, the researchers found that is a significant source of the noise that reaches riders” sensitive eardrums. It is the 1st time that the acoustic effect of helmets has been reported. These findings may incite or oblige, if governments get involved, helmet manufacturers to design quieter helmets and use the “riders’ ears protection” as a new marketing tool.