I live in a top floor flat (apartment), and have a real problem with sound travelling from the flat beneath me. The worst sound is either bass from a TV, or voices.
I paid a company a few years ago to install 'sound insulation', which they applied by means of an expandable foam which they sprayed between the joists.
I really don't believe that this had any affect at all, which was very disappointing as I paid a lot of money for this service.
It's very difficult to tell where the sound is coming from, i.e. I can't tell if it's riding up the walls, or coming through the floor.
On my floor, I have large joists with expandable foam between them, then floorboards, then plywood, then carpet underlay, then carpet.
Is there anything further I can do? or do I have to pay to get my neighbour's ceiling (beneath my floor) insulated in some way.
There is also the complication that there are eaves around the edge of my flat, so it's difficult to put insulation down across the whole floor (without removing the eaves walls) and I also can't tell if the sound might be travelling up into the eaves and coming through the walls.