| I don't know whether you've got one of the new shape ST's or the old shape, nor how big you are, but I know that I suffer from a certain amount of buffeting behind the standard old shape ST screen. I don't think that the standard screen flips the airstream over your head too well and the turbulent air spilling over the screen seems to hit your forehead.
I had a screen that I shortened myself. It didn't look that great but it put my lid in clean air and lessened the turbulence. So you might also want to consider a higher or lower screen.
Or get a Roof helmet, quietest lid I've ever worn. I still ride with earplugs but there's the inevitable time that you lose them at a fuel stop or something and the Roof lid is quiet enough not to need them. | 
Jools
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