Édouard-Léon Scott de Martinville patented his phonautograph on 25th March 1857. de Martinville recorded the oldest known sound recording of an audible human voice singing on the device.
Édouard-Léon Scott de Martinville patented his phonautograph on 25th March 1857. de Martinville recorded the oldest known sound recording of an audible human voice singing on the device.