Well, the male voice can certainly get down to 80 Hz, and probably below for certain basses, I don't think there are many people who actually talk that low--it takes an effort to get down there, unless you're Barry White. So I'd say that for virtually all movies sans singing (and serious singing at that--most popular male performers are tenors), you're not going to be hearing voices through your sub.

I am the Doctor, and THIS... is my SPOON!