Question

what happens to sound when it strikes a surface

Answer 1

When sound hits a surface such as a wall or a floor, several things happen. A proportion of the sound is: Reflected back into the room (energy is preserved). Transmitted through the surface and escapes from the room (energy is lost).

Answer 2

When sound hits a surface such as a wall or a floor, several things happen. A proportion of the sound is:

Reflected back into the room (energy is preserved).Transmitted through the surface and escapes from the room (energy is lost).Absorbed by the surface (energy is lost).

For the purposes of our discussion, we will forget about transmitted sound. Once sound energy has escaped from the room, it is no longer part of the sound field and can therefore be ignored.