If you have a great set of speakers but you still don't get the feeling of being ‘right there', there is quite likely an interference problem. Sound reflecting from the walls and ceiling can interfere with the sound coming straight from the speakers. This can make the sound seem slurred in time or it can make it seem like the tone is adjusted strangely. It can also make the stereo image less sharp and detract from the quality of surround sound effects. On the side walls and the ceiling, absorption reduces the size of these reflections and therefore reduces the amount they can interfere with the direct sound. Diffusion on the rear wall also reduces the problematic reflections but keeps the spaciousness of the room intact.