He had not been forgetful of "Visible Speech" all this while, but had been making experiments with two remarkable machines--the phonautograph
and the manometric capsule, by means of which the vibrations of sound were made plainly visible.
Listening to the recording, which can be found online, Roden produced a cameraless film by scratching ink-coated 16-mm stock, "notating" the music according to an aleatory and intuitive system of spontaneous marks--making himself a kind of human phonautograph
, but charging himself with the duty of subjective interpretation rather than mechanical recording.
It was made on April 9, 1860, by Parisian inventor Edouard-Leon Scott de Martinville on a device called the phonautograph
that scratched sound waves onto a sheet of paper blackened by the smoke of an oil lamp.