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.

The Special Purpose Tape Recorder (or Multi-track) was the first studio-oriented 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 afford composers the opportunity to alter and recombine pre-recorded sounds into a single musical output. This prototype version of the instrument used a three-octave keyboard to control the speeds of six tapes simultaneously, and then mix them down into a single recording.