Every Sound Is Sine Waves

A messy squiggle of sound going in on one side, a tidy list of pure, single-pitch tones coming out the other, and a row of everyday gadgets already quietly running that exact trick. This lesson is what the ninety-second video had no room for: what one of those pure tones actually is, why a sound is built from a stack of them, and where the trick starts to strain.

Before you start. Nothing. There is no maths here beyond doubling and tripling a number, and no physics you need to bring: the lesson builds every sound up from one smooth wiggle. Three later lessons lean on this one, Why the Siren Drops, Silence Built From More Noise and Watch a Particle and It Changes, so it is worth reading first.