A wave not only travels in space but it also propagates through time, so if the two waves can produce interference by overlapping in space they should also produce an interference pattern when they overlap in time, this phenomenon is called beats.
Beat Frequency :--
The beat frequency is when two sound waves with different frequencies come across each other, then their amplitude gets added and subtracted alternatively for a given time period. This leads to the growth of the sound to louder and softer.
The beat is a word used for sound waves. The beat frequency is the difference in frequency of two waves. ... In sound, we hear said beat frequency as the rate at which the loudness of the sound varies whereas we hear the ordinary frequency of the waves as the pitch of the sound.
