Leenia,

I have about 10 hours wearing time of noise cancelling headphones in helicopters, where it's critical to hear the radio which also comes through the headphones. I'm not nuts about them, they don't filter all frequencies equally, and when your head moves it alters the seal of the headphones, altering the effectiveness of the noise cancellation. The best noise cancellation seems to come at high frequencies, which is what you're probably bothered by in jet aircraft.

There's plenty of information on the web about how these things work. I'd start by going to Bose and to David Clark for a look at the technical details.

Most of my colleagues and I wear disposable ear plugs (I like Max brand from Howard Leight company) then put our headphones and or helmets on over them. I've never tried it with tape player headphones, but it's a cheap low tech solution you might consider.

D