I've got a pair of [1] in currently, no music, and they're doing a pretty good job of drowning out people talking at normal volume 6ft away. I'll admit they're doing a less good job of the strident conversation 10ft away and the plague of ringing phones but without music, I'm ok with that.

(NB. This reply entirely useless if you can't tolerate in-ear buds.)

[1] http://www.etymotic.com/consumer/earphones/ek5.html