I was recently reading an article in RIDE magazine (December 2010 edition), reminding me of the risk of permanent hearing loss in motorcyclists.
Motorcycle engines are largely exposed and normally rev at least twice as fast as car engines, so they generate a fair bit of noise compared to cars, even with a legal exhaust. But it’s not the engine noise or exhaust noise that is the problem. Rather it’s air turbulence around the rider’s helmet (especially around the neck region).
It’s tricky to measure noise levels inside a motorcycle helmet. You could create a helmet the size of a room, so that you could fit in your motorcyclist, the tester and all his kit, but that’s just a designer’s dream. There is an official method (ISO 11904-1) involving positioning a probe microphone at the entrance to the ear canal itself (though it will fit into just about any orifice, which is a problem if the tester gets bored). This is outlined in the approved code of practice (L108) accompanying the Control of Noise at Work regulations 2005.
Noise levels are typically found to be around 90 – 107 dB(A), depending on speed. 107 dB(A) is like standing next to a chain saw or jackhammer. Screen and helmet design can limit the noise level. There are even aftermarket skirts but, in my experience, they fall off within a mile or so. But a good deal of noise remains. This is not going to be too much of an issue for the occasional leisure rider. But, if you use motorcycles or scooters for work (like couriers, pizza delivery, or police motorcyclists), and especially riding at high speeds for long periods, hearing loss is likely.
Ear plugs are the usual answer and, in the main are very effective. In my experience, the first time you wear ear plugs on a motorcycle, it’s both uncomfortable and disorientating. It’s like you’re disconnected, like a video game with muted sound effects; it doesn’t quite seem real. But persevere and you get used to it.