Ringing noise at highway speeds

Recently at highway speeds, 55+, on mainly windy days my 2004 SLE will develop a ringing from the dash. It comes and goes as the angle of wind changes while driving. It sounds as if air is being forced in through the fairing below the windshield and resonating in the dash. Does this vehicle have a cabin air filter up there? Any ideas on what could be causing this noise?
Thanks,
Rob.

No cabin filter, you may have to tape areas around the w/s mldings and door frames where they meet the pillar to pinpoint the source.