Consider this: two singers are both singing an A4. These singers, like any human, are not perfect. One sings 440 Hz and one sings 441 Hz. So, theoretically, I should hear an amplitude oscillation with a frequency of one second, right? I never seem to hear this kind of effect, though it should happen if both members of a duet sing the same note, right? It would seem highly improbable that both singers would be singing the same exact frequency. Why do I never hear beats? The same thing for an orchestra. If the violin section is all playing the same note, if any of the violins are not tuned to the same exact frequency, there should be a beat. I don't hear these beats in orchestras either. Would the violins (or singers in the first example) just be 100% in tune or is there another physics concept explaining the absence of beats. It just feels a little weird that no violin would even be a tenth of a hertz off. Thanks.