Originally Posted by amolkold

Turn around and say, "Excuse me, but it's nighttime and I can still hear your conversation through my noise-canceling headphones & music. Would you mind talking in quieter voices? I would appreciate it." If the lights are off, you can add, "the lights are off and some of us are trying to rest."

I've gotten past the whole passive-aggressiveness and just ask people straight up what I want. This worked on a 9:30pm LAX-JFK flight. Besides, you won't see them ever again after you leave the airport, so who cares what their reaction is? And you never know if there are other passengers who are bothered by it as well but don't want to say anything ... you'll be a hero in their eyes.