Interference of Sound Waves from Two Audio Speakers

Sound levels are greatest at separations where sound waves from the two speakers interfere constructively, least where they interfere destructively.

Discussion

Each speaker approximates a point source of sound waves. As the speaker on the left is moved toward and then away from the speaker on the right, it passes through positions for which there is maximum constructive interference (sound level greatest) and maximum destructive interference (sound level lowest) of sound waves at the location of the microphone, which is above and in front of the stationary speaker. This is a three-dimensional example of interference of waves from two point sources.