Interference Interference is an effect caused by two waves of the same kind passing through the same space. It occurs with all kinds of waves, including sound waves, light waves, radio waves, and water waves.
Interference causes the intensity of waves to be stronger in some locations than in others.
The term interference also refers to any overlapping of radio and television signals with unwanted electromagnetic waves. The interference of sound waves can be demonstrated with two speakers connected to the same source of sound. If a listener is sitting at the same distance from both speakers, the crests of the two sound waves reach the listener simultaneously. As a result, the sound heard by the listener is four times louder than that produced by either speaker alone. This effect is called constructive interference.