In the 1860s, the Koenig sound analyzer revolutionized musical and scientific worlds by making sound visible. It demonstrated visually that musical notes and voices were in fact made up of simple sounds. Just like Newton's prism that spread white light into a spectrum of colours, the analyzer broke complex sounds into its basic sounds. These sounds, amplified by the spherical brass resonators, and then transferred as vibrations through the tubing, created intense bands of flickering flame in a rotating mirror.
The sound analyzer was a marvel of the age, captivating scientific figures such as Alexander Graham Bell, who used it for his pioneering work on "visible speech" for the deaf. Today, from digital recording to the study of bird song, the "pictorialization of sound" has become central to every aspect of modern acoustics.
See David Pantalony. Altered Sensations: Rudolph Koenig's Workshop in Nineteenth Century Paris. Springer, 2009.