Just curious, but for wood construction of multi-unit buildings I would think they have to use some kind of sound-proofing? Is it effective?
I lived in a 1960s-era apartment building for years. Rarely heard anything from the adjacent units, but occasionally did from the one above (loud music or TV, the odd disagreement). I don't believe there was any sound insulation, just thick concrete walls.
One year they replaced all the main water and drainage pipes, which meant certain walls were open for about a week. It was astounding how much noise carried through the risers, especially when the bathroom pipes were being replaced and my unit was separated from my neighbour by plastic sheets.

(I can laugh about it now, but what a huge pain that was... so much dust! had to clean the floors every night and keep furniture covered)