What is destructive interference?

Answer by  arj85 (19)

When two signals with different amplitude collide, they will subtract in waveform and produce a lower amplitude wave. A lower amplitude will result in more quieter sound.

Answer by  Henry55 (118)

Destructive interference is when the trough (at the bottom) of a wave and the crest (at the top) of a wave meet and cancel each other out (hence the name destructive), whereas constructive interference would be when the trough of the wave and the crest of the wave combine with each other.