Unfinished basement, to be used as music practice room

[Eric]

I just bought a home with a very large basement and want to convert one of the unfinished rooms into a practice space.  When I say unfinished, I mean there is no drywall up...just studs and joists.  The room I wish to convert has the concrete foundation on two sides.  The space above it is mostly garage and guest room.  
I am looking for an inexpensive & easy way to reduce sound escaping from the music space.  I don't necessarily need to soundproof the room, but that would be best.  Suggestions & tips anyone?  Acoustic drapes, carpet pad remnants, and egg-crate foam are a few options we were considering.