Beats are caused by constructive and destructive interference between two or more sound waves with different frequencies. The amplitude of the resulting sound wave changes over time relative to the difference in frequencies between the individual waves. This interference can be seen as a change in amplitude over time rather than just space, creating a beat effect in the overall sound heard.

1. Beats

2. Theory
 Constructive and destructive interference can be
measured as a function of time not just space
 A beat is the change in amplitude caused by two or
more waves with different frequencies
 The amount the amplitude changes is relative to the
difference in the frequencies of the individual sound
waves.

3. Theory
As shown in the figure, the
Blue and red waves are creating
constructive and destructive
interference resulting in the
green wave, which is the amplitude
we hear.