My dad often listens to music on his headphone while my sisters watch shows together and they'll be about 6 feet apart. The few times I've used his headphones there you have to speak up pretty loud to get through the headphones and whatever noise is coming out of them.
So yeah, if you have good quality over ear headphones you'll more than likely be fine.
There's some stuff on it in here. Plus a whole lot more info since it's a buyer's guide.
Edit, if you want to make sure, this one is in their list for entry level: "Shure SRH440, $75-$100. Great isolation, folds for portability, and detachable cable. Clean sound, somewhat neutral." They're
not very pretty but that'll keep the noise out.
Edited, Aug 19th 2012 4:43am by Aethien