It is absolute to have the nice sounding room for recording, mixing and mastering, not too many spaces have the acoustic quality to recording or mix audio accurately, that is why the treatment of the room is necessary. In this case, acoustic treatment comes handy.
The sound travels through the sound waves created through sound vibrations, and the room you are recording or mixing have walls, ceiling, doors, and windows. The main problems lie in sound diffusion and the sound wave absorption, some rooms absorb too much, make the room completely dead and some rooms are not able to absorb the excess sound waves completely.
Acoustic foams work very well, to get rid of the excess echo, you have to place acoustic foam on the walls or ceilings of the room if you have the problem with the sound absorption. But if your room is completely dead then you have to use diffusers to balance the room.