Fine, but the Fourier part is really in the violin and not in the human. Listening for beats is very old stuff in signals, and no doubt circuits and/or software

Fine, but the Fourier part is really in the violin and not in the human. Listening for beats is very old stuff in signals, and no doubt circuits and/or software are sometimes used to detect them; if so, then we can do the stuff with the beats without humans.