Theatre speakers are sometimes too loud, so headphones could also allow for a little volume control.

Sounds promising. My main concern is the potential conflict between those who want to use headphones and those who want the theater speakers to be REAL LOUD--for some movies you want to FEEL the sound.

Perhaps those newfangled noise-cancelling headphones would work well here.

Simply having some sort of ear-covering would protect those with earphones from the deafening sound that some people are afraid of, but I wonder if it's possible to perfectly - and I mean PERFECTLY - sync the sound in the headphones with the sound from the speakers.

If the audio track through the speakers was even a milisecond off from the sound in the theater, the sounds would be slurred and would sound terrible.

You could also use this idea to offer translation services. Like in a plane, you choose your channel. Channel 1 would be english and channel 2 could be spanish (or other)

In response to jgalston, there are already IR based headphone systems for the hearing disabled--these sync up well enough. Desyncs are more likely to happen at the production level (due to human error), rather than at the theater or between different outputs.

Overall, a hell of a lot of wiring would be needed. I predict more success if seat manufacturers were to offer this functionality. What a cinch for installers to just plug each seat into the next.