Air buzz at highway speed

[hispeed6]

Question for all of you. I live in Phoenix where the roads are pretty open as long as you're not dealing with rush hour. Anyway, I've noticed that sometimes at speeds above 75 I get a buzzing sound near the left side of my windshield. Anybody else get this? it goes away/diminishes with reduced speeds. Is air getting under a door seal or trim piece or what? Sound is too far forward to be the roof rack cross bows or the mirror and my windows are all the way up with the A/C on...

Thanks in advance

CJ

BTW, lux and adventure packages with chrome package plus cross bows.