This specific array of precision tuning forks are highly-specialized experimental forks that relate directly to Koenig’s long-standing disagreement with Helmholtz on the nature of combination tones. Some of them date back to Koenig's display at the 1876 Philadelphia exposition.

Videos:

The history of the tuning forks in the Koenig collection

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.