I'm going to be creating a dedicated home theater in an existing bedroom area and am now in the planning stage. This area is surrounded on three sides with "slump block" walls and I'm trying to figure out what kind of steps I'll need to take to achieve a reasonable amount of sound reduction through them. Is there existing knowledge that can give me immediate answers or what is a recommended way for me to find out what I need?
Slump block is a relatively common building material in the Southwest that peaked in the early 80s. It's essentially concrete block that is removed from the mold early so that the sides "slump". Here's a picture:
The existing walls are made up of 7 1/2" wide blocks, followed by a 1 1/2" fiberglass insulation and capped off with 1/2" drywall. It looks like so:
Completely regardless of its sound control properties, this wall is absolutely terrible from an insulation point of view (especially here in toasty AZ). As such, I've redone some of the walls in my house already to have a layer of 1 1/2" rigid foam (XPS) and then 3 1/2" fiberglass in 24" O.C. stud bays. That looks like this:
Okay, so with that in mind, I want to ensure that the noise from a blaring home theater will be essentially nullified by the time I get 15' from the room (outside). That is, my neighbor's property line starts 15' away and if he's standing right there, I don't want him to be able to tell if I'm even watching a movie.
I've run exactly one test on the existing wall. I took my (extremely loud) air compressor and set it going in the room. I then walked outside and noted that I could not hear it at all except by the windows (which are weak points on their own and will be addressed separately). I don't think that an air compressor, as loud as it is, is a great stand-in for a theater, though.
So... I'm not sure where to go from here. Is there a way for me to know if my standard insulation-friendly wall would be good enough on its own to hit my sound goals? Or would I need to create a different type of wall? How would I know and, if so, what?
Are there some kind of tests I could do now that would give me some ideas on where I stand before I decide on a design?
Any tips on where to go from here are greatly appreciated.