Two tones f1 = 440 Hz and f2 = 445 Hz produce a beat frequency of what?

Two tones f1 = 440 Hz and f2 = 445 Hz produce a beat frequency of what?

• A. 0 Hz
• B. 440 Hz
• C. 5 Hz
• D. 445 Hz

Answer: (C)

Beats come from the interference of two waves with nearly the same frequency. When you add the two tones, you get a fast carrier at the average frequency and an amplitude that wiggles up and down because the waves slowly go in and out of phase. The rate at which this loudness variation happens is the difference between the two frequencies. So, for 440 Hz and 445 Hz, the beat frequency is |445 − 440| = 5 Hz. You’ll hear five amplitude fluctuations per second—a tone near 442.5 Hz whose loudness modulates at 5 Hz.

Beats come from the interference of two waves with nearly the same frequency. When you add the two tones, you get a fast carrier at the average frequency and an amplitude that wiggles up and down because the waves slowly go in and out of phase. The rate at which this loudness variation happens is the difference between the two frequencies. So, for 440 Hz and 445 Hz, the beat frequency is |445 − 440| = 5 Hz. You’ll hear five amplitude fluctuations per second—a tone near 442.5 Hz whose loudness modulates at 5 Hz.