Quote Originally Posted by arbol View Post
I live in a condo with paper thin walls.

Is this a cost-effective solution to noise?
Kinda but not really. The studs will still transfer noise, especially low frequencies. If the guy below or next to you has a soundbar screwed to the wall, it's coming through regardless.

Spray in foam works better than cellulose and open cell foam is what studios use to absorb sound waves.

An effective way that some theater installers use is to build another insulated wall in front of the first with a gap between them filled with rigid foam (EPS) insulation. Obviously that too expensive for most of us.