Researchers said Friday that they have played back the oldest audio recording ever made, a 10-second snippet of singing made 17 years before Thomas Alva Edison patented the phonograph. Using technology originally designed to play records without touching them, a team at the Lawrence Berkeley National Laboratory was able to convert a series of squiggly lines etched onto smoked paper into an ethereal voice singing "Au Clair de la Lune, Pierrot repondit," a refrain from a French folk song.