(Originais Teachy 2024) - Question Medium of Physics

In the music industry, the precise tuning of instruments is a crucial factor for the quality of performances. During a recording session, a sound technician notices that a cello and a piano, both properly tuned to 440 Hz, produce a combined sound that exhibits periodic variations in sound intensity. By analyzing the phenomenon, the technician identifies that the resulting sound is a beat, which occurs due to the slight difference in frequencies between the sound waves emitted by each instrument. The intensity of the combined sound varies between the minimum and maximum 4 times per second. Considering this situation and knowing that the frequencies of the cello and the piano are respectively fV and fP, we want to determine the beat frequency (fb) that these instruments are producing. What is the beat frequency between the sound waves emitted by the cello and the piano, assuming that the difference between their frequencies is 3 Hz?