– What are overtones?
In: Physics
Say you play jump rope and whip the rope in a big loop. There is another way you can whip the rope twice as fast so two smaller loops form and the part in the middle stands still. This is a neat trick.
When you pluck a guitar string or hammer a piano string, something similar happens. The string vibrates like the jump rope making a big lobe. But at the same time there is another mode going on where the string divides into two and vibrates twice as fast. It doesn’t stop there, as the string also divides into 3 and 4 sections and so on. Every pluck generates these overtones.
Wind instruments like the trumpet are similar. When you play a low C you also get a higher G and a C and and E and so on. You can make your lips vibrate faster to play each of these notes as the fundamental.
So what is going on? Say the fundamental is 100 Hz. The string or wind column cycles 100 times a second. This is a G. There is also an overtone at 200 Hz which is another G. The next overtone at 300 Hz is a D, a perfect 5th. Then at 400 Hz we have another G. Then 500 Hz is a B. 600 Hz is another D, 700 Hz is sort of a sour note. 800 Hz is another G. When you play one note you get an entire chord.
When you play distorted electric guitar (square wave) fully 50% of the power is in the overtones/harmonics. The greatest instrument for learning about overtones is the Hammond organ; each draw bar dials in a particular overtone. Overtones are why a saxophone doesn’t sound like a tuning fork.
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