I notice it appears you're from Indianapolis - I too reside in that locale. In terms of your question - yeah, it doesn't soundproof a thing, really, although I've crammed a bunch of dense foam in my basement windowsills to help mute the escaping sound a bit (it does sound different on the outside with the foam in as opposed to it out).
My band practices in my cement basement, which has a cement floor and cement block walls. Obviously, there'd be a ton of ring if left unedited. So, i've put up some thick quilts and foam and blankets, and it does make the room sound much better. Sounds pretty good, in fact. Enough natural reverb to sound nice without too much noise and ringing. Of course, we're a pretty quiet band and practice at volumes low enough for us to speak up over, so that makes a huge difference too.