When a vibrating tuning fork moves towards a wall,why do we hear sound beats?

(N/A) When a vibrating tuning fork moves towards a wall,the sound waves emitted by the fork travel towards the wall and are reflected back.
Due to the Doppler effect,the frequency of the reflected sound waves perceived by the observer (or the fork itself) is higher than the frequency of the original sound waves because the source is moving towards the reflecting surface.
As a result,there is a slight difference between the frequency of the direct sound waves from the tuning fork and the frequency of the reflected sound waves.
When these two sound waves of slightly different frequencies superimpose,they produce the phenomenon of beats,which is heard as a periodic variation in the intensity of the sound.