[villagetinker]

I recall reading an article about this subject, the bottom line was for maximum sound deadening you needed to have a double wall with alternating studs that do not touch the other wall, and as I recall they used fiberglass insulation that ran around the studs and between them. As for the blown in insulation, you can do this your self I have seen rental units and bagged insulation. I did this up North, I drilled 2 holes one at the top and one at the bottom. I put a screen on the top one and the insulation was blow in the bottom one. You could tell when the wall was full from the top hole. I would do this first and see if it provides enough sound deadening, if not you probably need the double wall approach. Hope this helps.