Insulation actually does very little for sound PROOFing - most of that is accomplished with MASS and air space between the mass. In a typical home/project studio wall, the insulation is responsible for only about 6-9 dB of sound reduction - the rest is accomplished by having only TWO centers of mass, and only ONE air space. The greater the mass, the better the Transmission Loss (TL for short) the wider the air gap between the two centers of mass, the greater the TL. In any case, without TOTAL caulking of ALL possible air leaks in and out of the room, you're wasting your time. If you have single, hollow core doors, you're REALLY wasting your time.
Cruise more of the threads here on sound proofing, and you'll get a better idea of what's involved. Then, when you have a better idea, come on back and ask the other 99 questions you'll have by then... Steve