Additive synthesis is a method of sound synthesis that builds complex waveforms by combining sine waves with independently variable frequencies and amplitudes.

It was first applied in pipe organs: by controlling the routing of air through various pipes it’s possible to create a variety of timbres. The process of adding together so-called ‘partials’ to create more complex waveforms is used in synthesizers, beginning with the Telharmonium (1900) and, most famously with the Hammond organ in the 1930s. Envelope shapers and filters can further process the waveforms resulting from additive synthesis.