The phonautograph, patented by Léon Scott in 1857, used a vibrating diaphragm and stylus to graphically record sound waves as tracings on sheets of paper, purely for visual analysis and without any intent of playing them back. In the 2000s, these tracings were first scanned by audio engineers and digitally converted into audible sound. Phonautograms of singing and speech made by Scott in 1860 were played back as sound for the first time in 2008. Along with a tuning fork tone and unintelligible snippets recorded as early as 1857, these are the earliest known recordings of sound.