Ahh yes......that! As you've discovered it's caused by the peak vibrating. I taped the underside of mine with thick PVC tape....didn't work. I fitted screen edge trim to the leading edge of the peak....worked a bit. I rubber mounted the peak where it touches the helmet's shell.......didn't make a blind (deaf?) bit of difference.
I had however noticed that on the rare occasions when I forgot to wear my earplugs, the drumming didn't seem so bad. I then had a discussion with Cool Carbon who used to be a Green Leopard agent about the problem. He likened the problem to the noise that you sometimes get when walking while wearing foam earplugs. You know....the boing, boing, boing......noise that you get in your ears every time that your foot strikes the ground. He reckoned that the drumming was caused by mechanical transmission of the vibration from the peak through the bones of my skull causing the noise inside my ears.
That hypothesis made a lot of sense. I therefore decided to try some filtered ear plugs which would vent my ear drums rather than bunging up my ear canals with foam plugs. That's been the most successful solution to date. The wind noise isn't attenuated to the same degree as it would be with foam earplugs but the drumming is only just discernable. I don't know how bad it is for you but previously, at its worst, it was enough to vibrate my eyeballs and blur my vision.
HTH
