Waveform HarmonicsLesson 1 of 8

What Are Harmonics?

THE CONCEPT

Every musical sound is made up of multiple frequencies stacked on top of each other. The lowest frequency is called the fundamental — that's the pitch you hear. Above it sit harmonics (also called overtones): frequencies at exact integer multiples of the fundamental. 2× the fundamental is the 2nd harmonic, 3× is the 3rd, and so on. The number and relative loudness of these harmonics is what gives each waveform — and each instrument — its unique timbre.

TRY IT

Press PLAY to hear a pure sine wave at 220 Hz. Watch the spectrum analyser — notice there is only one peak, right at the fundamental frequency. A sine wave has no harmonics at all. This is the simplest possible sound: a single frequency, nothing else. Drag the FREQUENCY knob and watch the single peak move left and right.

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THINGS TO NOTICE

✦The fundamental frequency determines the pitch you hear.

✦A sine wave is the only waveform with zero harmonics — it's acoustically 'pure'.

✦The spectrum analyser shows frequency on the horizontal axis and amplitude on the vertical.

✦H1 marks the fundamental. H2 would be twice the frequency, H3 three times, and so on.

✦No instrument in nature produces a pure sine wave — all real sounds have harmonics.