Impact noise occurs when an object strikes another, making a sound causing a structural vibration on a wall, floor, or ceiling, resulting in noise on the other side of that affected surface. A good example is when you can hear footsteps on the hardwood floor of the room above in an apartment building. If the hardwood flooring was replaced with carpet, the footstep noise would be reduced significantly. The material of the carpet helps reduce the vibrations through to the structure.