Soundproofing a Floor (usually for those underneath)
Whether it’s a granny flat, a music studio, drum practice room, home theatre or rented room, hearing thuds and clicks from someone walking upstairs is a problem. It’s even worse if you can hear them talking (and they can hear you). So this type of soundproofing is critical to a quiet life.
The first thing to realise is that acoustic foam won’t make much difference, if an at all. Carpet on top of the floor may help. In reality, the transmission loss of the floor needs to be improved. Most commonly, in timber house constructions, this is a good solution - wooden floor soundproofing
Underneath a concrete floor, adding a layer of plasterboard to the concrete will do very little. It’s better to add the plasterboard to a batten, creating a cavity, and insulating the cavity.
Make sure that other paths for sound to follow are fixed before you go improving the floor. Penetrations for lights and air conditioning, stairwells, windows, pipes etc can all allow lots of sound to bypass any work done to the floor.