I didn’t measure it unfortunately. It definitely didn’t stop everything, I could still hear a lot of stuff, but it just dulled it enough that it was easier to t

I didn’t measure it unfortunately. It definitely didn’t stop everything, I could still hear a lot of stuff, but it just dulled it enough that it was easier to tune out. I think most of the sound was actually echoing through the ductwork and leaking past gaps in the doors rather than going through party walls so if it was actually possible I’d try to get in there. Ideally though, the soundproofing needs to happen in the room where the sound is happening rather than in your space. The building I’m in now reserves the right to require you to put rugs down if your neighbors complain. When I got a dog I put a bunch down so the downstairs neighbors didn’t have to deal with the constant patter of his feet.