I’ve lived in many apartments and it’s quite variable. I agree with Seagoon it depends on construction. Currently I don’t hear a damn thing even if in the hallway can hear my neighbours loud music. I’ve also lived in an apartment where I could hear my upstairs neighbours footsteps, my across-the-hall neighbours’ wailing (he was quite unwell), and it had double height, full wall glass as the outside wall, and I could hear the voices of people on the street. That apartment almost drove me insane and I had to break the lease and leave early and significant cost.