I like electronic/ambient/space music ... which my wife refers to as "that noise you listen to." Getting to our son's school is a five hour drive. I bought her a pair of Able Planet Noise Canceling headphones -- they work better than I could have hoped! She listens to her Pop music on her Ipod with the headphones and I can listen to my music in the car's CD player. They run for hours on a AAA battery. They are "folding" headphones, but the hinge is too gimmicky for me -- I just leave them unfolded.
Actually, I got a pair for myself, too. They really do work really, really well. The cost was only about $50 at Costco, here in the states. Amazon (US) carries them.
Of course, they won't help if you can "feel" the bass!