Scott’s 1860 phonautogram was made 17 years before Edison received a patent for the phonograph and 28 years before an Edison associate captured a snippet of a Handel oratorio on a wax cylinder, a recording that until now was widely regarded by experts as the oldest that could be played back.

Mr. Giovannoni’s presentation on Friday will showcase additional Scott phonautograms discovered in Paris, including recordings made in 1853 and 1854. Those first experiments included attempts to capture the sounds of a human voice and a guitar, but Scott’s machine was at that time imperfectly calibrated.

“We got the early phonautograms to squawk, that’s about it,” Mr. Giovannoni said.

But the April 1860 phonautogram is more than a squawk. On a digital copy of the recording provided to The New York Times, the anonymous vocalist, probably female, can be heard against a hissing, crackling background din. The voice, muffled but audible, sings, “Au clair de la lune, Pierrot répondit” in a lilting 11-note melody — a ghostly tune, drifting out of the sonic murk.