There is very little more frustrating to me than getting 9 hours into a 13 hour flight, and having the batteries in my noise canceller run flat. Airliners are _

There is very little more frustrating to me than getting 9 hours into a 13 hour flight, and having the batteries in my noise canceller run flat. Airliners are _loud_... (I have an inexpensive set of cabled noise cancelling earphones that run off a single AAA battery, which always gets packed in my carryon...)