Hi there... I actually didn't, it's just normal drywall. The wall insulation between the studs behind the drywall really deadens a good bit of the outside sound but most importantly is your entry door you walk through. I put in a bit more expensive (TM Cobb) quality and thick door which seals perfectly when you close it. Creating that seal blocks out a ton of outside noise and is critical. Clients walk in and when we close the door, they say whoa is this room soundproof (it's far from being soundproof though). The other important thing is putting plenty of furniture and a rug etc. to stop the sound reflection off the high ceilings and hard surfaces. Recording isn't too important for me so I didn't take it too far. We just sold our house and the buyer actually works closely with Cliff Martinez (they usually write music at the buyers house so apparently he and Cliff will be in this space recording his next score... which blows my mind) and he plans on installing all those sound deadening panels every where to really quieten the room. Best of luck on your project!