The sound synthesiser was Helmholtz’s clearest instrumental expression of his theory of timbre, or sound quality. Whereas his spherical resonators dissected compound sounds (vowels or musical sounds) into elemental frequencies, the synthesiser did this by building up complex sounds from simple frequencies. In 1857 he went to the instrument maker Friedrich Fessel of Cologne to turn this idea into reality. The initial instruments used a combination of electrically driven tuning forks, resonators and piano keys to synthesise compound sounds.

Tone-limit apparatus, for high notes of high pitch.

Made by G. Appunn & Sons.

            This apparatus was designed for determining the highest vibration-frequency which is recognized by the ear as a musical tone. It consists of 31 small tuning forks, giving the diatonic scale

The Sonde is a studio-oriented musical instrument designed by Canadian physicist Hugh Le Caine and built in the National Research Council of Canada’s (NRC) Electronic Music (ELMUS) Lab in Ottawa, Canada. It was created to facilitate experimentation in additive electronic sound synthesis. Unlike subtractive sound synthesis, in which a complex waveform is “shaped” by filtering or removing different frequencies, additive synthesis requires building up a complex waveform through the simultaneous introduction of multiple simple waveforms.

The Polyphone is a performance-oriented musical instrument designed by Canadian physicist Hugh Le Caine and built in the National Research Council of Canada’s (NRC) Electronic Music (ELMUS) Lab in Ottawa, Canada. It is the world’s first known keyboard-based electronic synthesizer that allowed for multiple notes to be played at once. Its name, Polyphone, is derived from this polyphonic capacity. It permitted musicians, for the first time, to play a synthesizer as they would a piano or organ: with two-hand accompaniment and multi-note chords.

The Serial Sound Structure Generator is a studio-oriented musical instrument designed by Canadian physicist Hugh Le Caine and built in the National Research Council of Canada’s (NRC) Electronic Music (ELMUS) Lab in Ottawa, Canada. It was created to expand upon the serial composition technique of using the repetition of a series of notes, typically a series of 12 tones, to create a musical composition.