A Welte-Mignon Reproducing Piano is what we commonly know as a pianola: basically, a machine that’s able to encode all the details, dynamics and nuances of an interpreter’s playing onto piano rolls, so they can be reproduced later by a player piano. In the late 1913, Claude Debussy sat and recorded 14 pieces on one of these Welte-Mignons, including the song reproduced in the video below, “La soirée dans Grenade,” from Debussy’s 1903 Estampes (“Prints”).
According to this post published by Open Culture, “Debussy was 52 years old and suffering from cancer when he made his piano roll recordings. He died less than five years later, on March 25, 1918.”