To reduce helmet buffeting:
1)…Channel some air from the front of the windshield to the rear with 1 inch to 1.25 inch PVC pipe and one 90 degree elbow. The elbow will face the front, below the windshield. The other end will face up, behind the windshield. (Link to article: https://www.hondarebel3forum.com/threads/helmet-buffeting-partial-fix.15648/)
2)…Add a vent to your windshield.
3)…If your fairing has a detachable headlight cover, remove it, or add 12 mm spacers to make a gap.
4)…If you are looking for a new helmet, get a quiet one like a Schuberth C3 Lite or Schuberth C3 Pro.
5)…A Clip On Windshield Extension / Spoiler / Wind Deflector / Laminar Lip can reduce turbulence and wind noise.
6)…Get a bigger windshield.
member comment: “I’ve got the C3 pro helmet and the noise after fitting the windshield increased dramatically, so I installed a wind deflector (item 5 above), problem solved”