How do you prove that a sound source at a distance d from a wall will produce a interference pattern as if the wall was removed and another sound source was added with 180degree phase difference at a distance -d.

Question

anonymous · Answer

Draw the sinusoidal sound wave as reflected from all (180o phase change), then draw the sound wave expected from distance -d  and draw the incoming sound wave. Note how the incoming combines with each of the other two.