That just does not work unless you have bubble around your whole body and I bet even then it’s sufficiently loud.
Unless you find the perfect windscreen, most have lots of buffeting and it’s actually quite hard to dial it in perfectly.
Helmets do absolutely zero to block noises.
Edit: just to add. I think it stands. The helmet does not block any sound. It may be aero dynamic enough that it helps prevent additional wind noise but it’s not blocking sound. Ear pro all the time.
Said it in another thread but while sure it matters, it’s generally a pretty weak argument. It’s your ears and you can decide for yourself but even if it does not sound loud, over the course of a ride it can still be high enough to slowly cause damage.
To me it’s the same kind of argument of friends who would say it’s ok to shoot shotguns without ear pro. Sure it can be done but it adds up.
And I don’t mean this the wrong way. Your experience is anecdotal. Maybe you ride in a city and slow speeds, maybe you have a windscreen that actually does decent job of creating a bubble over you, maybe you don’t ride for extended periods of time. Too many variables to account for. For the population though, ear pro is recommended for Motorsports. I had a bike once that caused buffeting from the hand guards. It might work for you but generally does not work for many.
My Shoei RF 1400 was extremely quiet. Supposedly one of the few helmets that you actually don't need ear plugs with unless you're going extremely fast.
I would be willing to bet the db was high enough to cause damage over enough time. It’s not just just the peaks but also the duration. I would be very surprised if generally helmets provide much if any meaningful db reduction.
Unless you find the perfect windscreen, most have lots of buffeting and it’s actually quite hard to dial it in perfectly.
Helmets do absolutely zero to block noises.
Edit: just to add. I think it stands. The helmet does not block any sound. It may be aero dynamic enough that it helps prevent additional wind noise but it’s not blocking sound. Ear pro all the time.