Question

Beat frequency derivation

Answer 1

Beats are often observed between two vibrations with similar frequencies. The beat frequency equals the difference between frequencies of the beating signals. When sound signals interfere, the beat signal can sometimes be heard as a separate note: the Tartini tone. Both are useful and important in practice for measuring frequencies and for tuning musical instruments. (It is also worth looking at for the insight it gives to Heisenberg's Uncertainty Principle, as we shall see below.)