Question

What are beats?

A: periodic fluctuations int he velocity of sound waves

B: periodic fluctuations in the wavelength of sound waves

C: periodic fluctuations in the intensity of sound waves

D:periodic fluctuations in the frequency of sound waves ​

Answer 1

In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies. With tuning instruments that can produce sustained tones, beats can be readily recognized. So I believe D.