Using Roxul Safe and Sound is a great way to help soundproof your room. The wife and I just did the media room in the basement of our house that is being built. We added the Safe and Sound to the ceiling from the media room and it was virtually pressed into place. A few areas may need to be carefully placed with caution if you have ceiling lights, make sure you have Insulation Contact (IC) lights in order to use the Roxul in the ceiling and close to those recessed lights, otherwise, you must be at leat 3" inches away from those cans in the ceiling. This stuff made a night and day difference in the room, wife tested by walking upstairs and yelling, could barely hear her. This was prior to the drywall install.
You can get Roxul at Lowes in 16" or 24" OC. The batts are 3" thick, but compress easily.
I also did our laundry room on the top floor. If you cannot remove the drywall, use QuiteRock drywall, anything above the 510 series would help you.