I am with RR here.
What I see time and again in helicopters is that just because the machine / spares / maintenance has to be exacting and therefore costs the earth anything associated with helicopters "must" justify an exhorbitant price.
It isn't just helmets but many other things - starting with ground handling devices (a powered fork-lift truck, after all, which costs less than £1k can be easily adapted to do the job of a £5k "specialist" device) but I don't want to thread-hijack). Sticking with helmets:
The violence exerted on your head in a motorcycle accident is impressive. A helmet that can withstand that is certainly going to sail through a roll-over.
And which motorcycle visors are not shatterproof?
Not sure about the sound attenuation - not my field - but have you ever ridden a bike? Wind, road and bike engines are not silent.
I have some insight into the economics of Defence equipment and I don't share your "it cost the earth, it must be tested and it must be good" view. A serving friend of mine buys his some of his own equipment rather than use the stuff provided (and I am talking about the stuff that goes "bang" as well as boots, weather-proofs and other material). Luckily he is in a regiment where that is allowed.
I suspect that much of the cost comes from small production runs and a desire to hit a certain profit margin. If someone convinced the motorcycle helmet manufacturers to adapt one of their designs it would give them an additional outlet at marginal costing and we would all have access to a truely effective and competetively priced helmet.
Rant over - does anyone know the CEO of a helmet manufacturing company?
John