The pool noodle is a good idea.
But as the others said, twisting the straps will alter the airflow over them and stop the annoying hum.
I have to twist mine not only over the portion that crosses the center of my kayaks but also from the gunnels to my roof rack. (I carry my boats hull-side down.)
If I don't do the twist it's a very noisy ride.
Olive Hobie Revo 13
Hidden Oak Native Ultimate 12
Author: The Simple Joys of Kayak Fishing (Tips and Tales From an Old Guy in His Plastic Boat)
Available on Amazon.com