Final answer:
Beat frequencies of 21 Hz, 22 Hz, and 43 Hz are produced when the adjacent piano keys of F, F-sharp, and G with frequencies of 349 Hz, 370 Hz, and 392 Hz respectively are struck simultaneously.
Step-by-step explanation:
When three adjacent keys on a piano are struck simultaneously, the keys of F, F-sharp, and G producing frequencies of 349 Hz, 370 Hz, and 392 Hz respectively, they create a set of beat frequencies due to the phenomenon known as beating. Beating occurs when two waves of close frequencies interfere, leading to a fluctuation in the amplitude of the sound wave. This can be heard as a pulsation or beating in the sound.
The beat frequencies are found by calculating the absolute differences between the individual frequencies. Hence, the beat frequency between F (349 Hz) and F-sharp (370 Hz) is |349 Hz - 370 Hz| = 21 Hz. Similarly, for F-sharp (370 Hz) and G (392 Hz), the beat frequency is |370 Hz - 392 Hz| = 22 Hz. There will also be a beat frequency between F (349 Hz) and G (392 Hz), which is |349 Hz - 392 Hz| = 43 Hz.
Therefore, the discordant combination of these three piano keys will produce beat frequencies of 21 Hz, 22 Hz, and 43 Hz.