The physics of viola harmonics

It just struck me that no one explains this — how they work. I don’t mean the harmonic series that results in the overall color of a given note. I mean the whole “touch the string as lightly as possible” business where the viola suddenly sounds like it’s acquired a falsetto. (Same thing with violins and cellos, and I’d imagine basses as well.)

People should understand this — why it happens. Until I sussed out what was going on, I had trouble doing it, but now even a goob like me can do it reliably.

I should write something explaining it — for real. Just going through all the various harmonics and explaining why they happen the way they do. It’s not hard. At bottom, it’s about not so much “cutting” a string by pressing down on it so that only the part between your fingertip and the bridge vibrates. It’s about imposing a non-vibrating node at a given spot on a string with your fingertip, pressing lightly enough so that the whole string can still vibrate even though that one bit under your finger is held still.

I need to make some illustrations.