hardware, i'm gonna disagree with your description of turbulent flow. hard to demo without a wind tunnel and streams of smoke, but i think that air coming over the top and hitting me in the chinbar is laminar flow, nice and smooth, not turbulent. turbulent implies eddies and chaotic flow patterns.
otoh, once it hits the helmet, that square edge at the bottom of the helmet induces eddies and creates the majority of "wind noise" on a moto (shrug your shoulders, it'll quiet down). that's definitely turbulent. probably every helmet will create some, it's just a matter of how much, based on shape and the placement of the helmet in the airstream.
imho, not worth a lot of effort or money to fix wind noise, you'd have to make that still air pocket huge. vetter windjammer on a versys. earplugs are cheap and easy.
the turbulence that causes helmet buffeting happens, i think, further back, in my case too far behind me to matter. the buffeting would be the result of the turbulence induced by the imperfect aerodynamics of a human on a motorcycle... airflow over and around your body, sucked into the vacuum at your back, pushes your helmet around. this, i imagine, would suck.
There are some huge windshields out there that probably do a great job, but they look like ****.
ain't that the truth! it's gotta be a serious problem to inspire such fuglification. do any of you cats in search of the perfect screen wear earplugs? are you trying to cure buffeting or noise?
i don't get the buffeting and i wear earplugs, so i'm just curious. i once rode a transalp that had one of those gigantic screens and that was the only time i ever felt buffeting on a moto. i also didn't appreciate looking thru it, the distortion was disconcerting. so i wonder "why?" every time i see those barn door screens.