A real easy test to determine a solution is take some cardboard, fold it to be about a half inch thick, and stuff it between the dash and windshield (between the driver side speaker grill and the large semi-circle piece where the clock is). Move it around or add others if the noise does not stop. I currently have a piece in my car.

Once you have determined the location of the noise, acquire some black foam (pipe insulation works well) and stuff it in the needed locations.