I had the same issue at the upper left portion of the windshield. How I came to find out the problem though was kind of crazy. I had to have my windshield replaced bc of a serious crack from me being a dumb$$s. I was changing out wiper blades and lost hold of the drivers side wiper arm. The arm smacked the windshield and sent a crack all the way up. I have since learned to put a pad behind the wiper arm when changing out blades.
Anyway, after having the windshield replaced there developed a whistling noise coming from the top left near the drivers visor. It would begin at around 35 and get worse with speed. If I pushed on the windshield it would get louder. It turns out that the replacement windshield was defective and had to be replaced. The air was coming through between the seal and the glass. Our trucks do not use adhesive, they rely on a type of rubber seal that is installed with a special tool. If you push on the windshield while driving you should hear where its leaking. It whistles bc the air is going over the rubber just like if you held a piece of grass between your fingers and blew on it you would get the same type whistle.