Never thought of a full face being more noisy. I have always rode with a full face. Rode once without a helmet and made me feel naked. It does make sense that a full face is more noisy than a half. More closed space fore that big motor to echo. Ill never ride without a helmet. I was raised to put one on even if I was riding my dirt bike from the garage to the house. That was only about 50 feet. And plus my wife sais she would take the valk away if she caught me without one.
It's not engine noise or exhaust (bone stock), it's
roaring wind noise .... even on an interstate with OE shield. And it's a top quality Icon helmet with thick foam on the bottom (tries to rub my ears off putting it on, though a perfect fit once on). It's Ok, I really do not like wearing it anyway except in the coldest of riding. And I am a helmet guy too... not that I wouldn't like to take it off somewhere out West with no cars/traffic for a hundred miles. But since I get sunburn and skin cancer on my bald head, that's out anyway. I have not fallen off a bike on the road since 1971, but I won't ride without one anyway.