I use in-hear sound isolation headphones, which "seal" the ear to passively block out ambient noise. Bonuses are: doesn't require power, and can be used during all phases of an airline flight without getting nasty looks from the attendants (though you may find it more comfortable to remove them during ascent/descent to allow pressure equalization).

Here are some suggestions that you might find helpful... http://www.headphone.com/selection-guide/in-ear-headphones.p...