I agree with some of the points made in previous posts as I've found that there's a lot more to consider than just finding a quieter helmet.
My RF-1100 got quieter when I replaced the Yamaha double-bubble windscreen with a Puig racing screen because of reduced turbulence around my head. It got quieter again when I bought the gsx-r600 because of reduced turbulence despite the lower screen. Fairings don't necessarily create cleaner air for everyone - that's why Marthy swears by the little screen on his fz-09.
My Scorpion t1200 is quieter when I'm riding the gixxer in the normal ss position with my face turned slightly down. Racing helmets and touring helmets are usually designed for different aerodynamic conditions, but the t1200 seems to be more race oriented.
Both helmets are quieter when I'm wearing my Icon rain jacket because the rolled up hood around my neck doesn't allow much wind to enter the helmet from the bottom.
It's going to tough to find the ultimate helmet around here because we all have different head shapes, set-ups, riding positions.
There's some good information online - I personally like Revzilla because they offer good video reviews and good advice.
Good luck. I hope you find something that works for you.
btw, +1 on earplugs
I don't think the windshield blasting air at me is an issue. I am pretty tall and I had to lean way down to finally notice the difference. With the way our bikes our, I ride pretty straight up, but I noticed that if I looked straight down (obviously not very useful while riding) almost all the wind noise went away but I started to get the low pitch booming sound. There was a sort of happy medium in between straight up and straight down, but it wasn't very comfortable.