Underlay for impact sound

These materials will help reduce the tap tap tap made by hard sole shoes on a hard floor. They don't offer anything for areas that are carpeted. They also offer nothing for the thud often associated with walking across a timber joist floor. To reduce this requires mass and stiffness. Mass can be added above and below the joists using additional layers of plywood or plasterboard and the cavity within the joists should be filled with a rock wool type fibrous insulation this will also help with airborne noise transfer (voices, tv etc). Stiffness can be improved using a technique called stepped blocking which uses noggins between the joists to stiffen up the floor.