A triangle wave is a non-sinusoidal waveform named for its triangular shape.

A bandlimited triangle wave pictured in the time domain (top) and frequency domain (bottom). The fundamental is at 220 Hz (A2).

Like a square wave, the triangle wave contains only odd harmonics. However, the higher harmonics roll off much faster than in a square wave (proportional to the inverse square of the harmonic number as opposed to just the inverse).

It is possible to approximate a triangle wave with additive synthesis by adding odd harmonics of the fundamental, multiplying every (4nāˆ’1)th harmonic by āˆ’1 (or changing its phase by Ļ€), and rolling off the harmonics by the inverse square of their relative frequency to the fundamental.

This infinite Fourier series converges to the triangle wave:

Animation of the additive synthesis of a triangle wave with an increasing number of harmonics
Triangle wave sound sample
5 seconds of anti-aliased triangle wave at 220 Hz

Problems listening to this file? See media help.

See also

Sine, square, triangle, and sawtooth waveforms

Categories: Fourier series

 

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