Yes, if the room is finished with sheetrock you remove the sheeetrock and extend it away from the studs with absorbing material instead of screwing the sheetrock directly to the studs.
The more absorbing material you have the higher you have to turn up the volume and the higher you turn up the volume the more absorbing material you will need.
The more absorbing material you have the higher you have to turn up the volume and the higher you turn up the volume the more absorbing material you will need.