Hmm maybe if you have a wooden door and huge sound leaking outside disturbing house mate, then precisely sticking this foam around the door without any gap will prevent the sound from going out.

If your room is made of wood then sticking this foam to cover the room will significantly reduce the sound from leaking outside, but for concrete wall it will reduce maybe abit..unless your concrete wall is very thin or lots of air bubble inside due to poor workmanship.
If you plan to build a giant theater system ....these foam will greatly reduce the sound from leaking outside regardless of any wall ... like Cinema if they use this foam the sound will reduced by huge percentage.

Hi, Our foam is 10 square feets, or 6 feets X 20 inches.
It depend on your usage and listen pleasure for how many refection you need to kill for your room, the more you paste the less echo you have.

Bitd by bits will retain room feel, whole side wil kil reverb at from that side.

yap

Double side tape doesn't work. Either glue spray or the best budget is using dunlop glue.

We sell in small qty too.