I went with two sets of noise cancelling headsets:
1) Coby CY-191 headset – $30 or so at Frys.
2) Philips HN060 earbuds – $60 or so at Frys.
Given the long flights through Japan and all, it seemed like a good idea.
Throughout the flights, I used both the cheap foam things you can get for pennies at any hardware store and the noise cancelling headsets.
Bottom line: I used the Coby set. They filter the high frequencies and shut out the rumble. I took the Philips set back. They seemed to have no effect! Very odd. Perhaps they were broken out-of-box. Tried multiple batteries and all the usual tricks to get them to work. No luck.
The Coby set’s plastic over-the-head-band broke in the car within a week or two of returning. I had been using them while driving. Nice. Removes a lot of road rumble and hissing. Leaves audio and horns to be more easily heard. Old car.