Simulation of acoustic waves bouncing on a quadratic residue diffuser, vs a flat surface. The lines of energy can be thought of as stretched out impulses. The oscillating sources at the upper middle acts as a loudspeaker. Made using the ripple tank java applet at falstad.com.
Without using a lot of math, this video demonstrates how acoustical panels reduce reflections to improve sound. Comb filtering, standing waves and rooms modes affect how sound waves are reflected within a room. Properly placed acoustical materials such as acoustical foams, fabric wrapped panels and diffusers will prevent destructive reflections and undesirable specular artifacts.
Filmed and produced by Ryan Larkin. Narration by Joe Horner.