Id say ditch the helmet all together and just get a headset like this
maybe just wear it without it being plugged in. If you wear it tight against your ear it shouldnt move too much.
another option is to get one of those m88 helmets, they have ear protection built in. I bought one for like $10 off airsoft-club.com, they will protect your ear, but if your like me, they make you feel like a giant bobblehead. I hate the stupid thing lol. Lots of people buy the bike helmets and mod them, I have one, I like it, doesnt really do anything for the ears mind you.
another option is to wear whatever you want and just get a mesh lower mask that covers your ears like this
