Most pitched instrument tones reduce to patterns of harmonics generatable from sine, saw, square, or pulse waves

The starting premise of subtractive synthesis is that the tones of most real pitched instruments can be reduced to patterns of harmonics, and those harmonic patterns can be generated using a synth’s basic oscillator waveforms — sine, sawtooth, square, or pulse. Choosing a waveform whose harmonic content is close to the target, then subtracting (filtering) what is not wanted, approximates an instrument’s timbre. Unpitched percussion is the exception and needs a different raw material (noise and inharmonic spectra) rather than these harmonic waveforms.

Examples

Approximate a bowed-string tone with a harmonically rich sawtooth then filter; reach for noise instead when synthesizing a snare.

Assessment

Explain why subtractive synthesis starts from harmonically rich waveforms, and why percussion needs a different starting material.