Depends on the environment, and whether you can tolerate proper earphones with a good seal. If you can, they provide pretty good isolation without mucking with

Depends on the environment, and whether you can tolerate proper earphones with a good seal. If you can, they provide pretty good isolation without mucking with the sound. If you can't, then noise reducing can will knock back the surrounding noise (I've seen people use them on planes to sleep, for example). But to me, they nuke the high end - YMMV. I have a pair of Etymotic ER4P's. Ety's are pretty good earphones, but so are Shures. Cans, like speakers, are something that must be experienced first-hand. It depends on your ears, the kind(s) of music you listen to and the quality of the signal path and signal.