I'm close to 6 and a half feet tall so I'm pretty sure that I have it at the top position. I remember recently moving it up/down to find the best position for comfort.I noticed that moving the seatbelt tensioner (I think that's how you call the think on the pillar to adjust the height of the belt) to the top position solved by quite a bit this problem for me. It still rattles sometimes, not so loud or as often though.
There were two main causes for me.
1. Try lowering the window just a bit, so that it doesn't let air in, but it is lowered a bit, a few mils only.
2. Raise the seatbelt tensioner all the way to the top.