Why Does Singing Together Sound Good?

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An octave is exactly double.

A note vibrating twice as fast as another sounds so alike that both get the same name. Every two waves of the high note fit one of the low — the simplest possible fit.

Step 2 of 5

Other sweet pairs are simple fractions.

Three wobbles against two, or four against three, also line up neatly and sound pleasant. The simpler the fraction, the more settled the pair sounds together.

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Clashing notes beat against each other.

Two notes very slightly apart drift in and out of step, and you hear the loudness pulsing. That throbbing is the roughness — and singers use it to tune themselves.

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Harmony is people choosing simple ratios.

A choir singing in parts is several people holding notes in those neat fractions at once. It sounds full because the waves fit together instead of grinding.

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Singing together locks people in.

Voices in a group drift towards each other, because the roughness of being slightly off is unpleasant and everyone corrects it. Breathing falls in step too, which is part of why it feels good.

Different musical traditions cut the octave into different numbers of steps. The octave itself is agreed on everywhere, because doubling is not a matter of taste.