You should really consider etymotics ER-4P. They invented this sort of system and make high end audio monitors (like rock stars use on stage) and hearing equipment.

http://www.epinions.com/elec_Audio-H...splay_~reviews

I prefer the foam inserts myself, this provides in excess of 40db of noise isolation. You simply won't hear the stewardess, the engine, or the squaling infant. What you WILL hear, is stuff deeper in the music tracks and background noises that were also recorded. Unlike the others (including the Shure) the ER-4P uses a stalk system that places the speaker farther in your ear canal in a hole in the center of the isolation foam. This delivers the actual speaker almost directly to your ear drum without any background. There is simply NO background noise and you will be stunned by the mistakes and other things on the tracks you were never aware of before.

Regards,
-Bouncer-