In this video, David Pantalony, Curator at Ingenium: Canada’s Museums of Science and Innovation, demonstrates a 19th century vowel synthesizer.
The instrument is a Hermann von Helmholtz synthesizer, invented in the 1860’s and built by Rudolph Koenig. The Helmholtz synthesizer was designed to explore how additive synthesis can be used to create complex sounds from simple ones, and how sine waves can be combined to create different timbres, vowel sounds and more.
Helmholtz’s synthesizer generates sounds using a series of tuning forks, each pitched to different frequencies, made to vibrate using electromagnets. A keyboard is used to control the volume of each pitch, letting you play the pitches individually, or combine them as overtones of the fundamental pitch to do additive synthesis.
While this is clearly a synthesizer, it was designed primarily as a scientific instrument, rather than a musical one.