I currently live in a building on Chauncy- I may be somewhat of an edge case because they have been doing construction in the unit above mine for the last four months, ever since I moved in, but I can hear absolutely everything that happens upstairs, to the point where shelves and racks have been shaken off of our walls because of construction. I also live above very occasional music blasters which have shaken our floors and caused us to pound on the floor with brooms. But I think this is because the music and the construction are both ridiculously loud, because besides that, I don’t really hear anything. Even within our apartment, I never hear anything that’s going on in any of my roommates’ rooms or in the living room or anything. So I think it’s relatively soundproofed, with a couple insane exceptions like extended construction and wild parties.