This word will be used more and more in the future as kids who are now driving around with mega-bass speakers in their cars turned up to 12 will not be able to hear anyone speaking to them in normal tones by the time they are 30.

I would suggest that they begin to practice saying, "Pardon me?" It's a much more polite way to say, "I can't hear shit; come again." But even that would beat, "Huh?"