whisle/humming noise in 02 trailblazer

[michigan2500hd]

The wife came home the other day and said the trailblazer was making a weird noise so i drove it and it sounds kinda like a wind noise whisling. Hard to pin point the exact area but its somewhere around the windshield or front half of the truck. Starts at about 38 mph and increases in pitch with speed. The noise started all of a sudden so i cant think its the bug shield or window visors cause they have been on for over a year with no problems. Help please, thanks

[Wirenut]

I used to have an o2 TB and had the same problem. I put a bug shield on the hood and it stopped. My whisle noise was around the driver side mirror. I would put my hand on the bottom of the mirror and it stopped.