Under, I just got a bad lt. and they are really nice under.
How do they fit you ask? I put the straps over the tops of my ears so they don't hurt and then put the strap near the top of my head. As i'm putting on my helmet, there is a little flap in back which I put the clasp for my smith fuses right under. I basically lift up the flap so it holds my head right underneath the clasp. It makes it so I can hardly feel them when they are on, looks sweet and functions excellently.