I've been using active noise cancelling headphones on long trips for a while now.
They sit snugly in the ear canal, but I like to tape them in place with micropore tape (can come loose when putting a helmet on).

They are fantastic. In fact they are so good, you won't notice much in the way of wind noise or engine noise. Spooky! There seems to be an amplification of some mechanical noises (gear changes etc.) which can be disconcerting at first.

Not sure about the legalities but works for me.... Boneman