Information Week:

The recording
played Thursday predates Thomas Edison’s invention of the phonograph
(previously thought to have recorded the first sound) by 17 years. It
captured about 10 seconds of the French folksong “Au Clair De La Lune”
on April 9, 1860.

Édouard-Léon Scott de Martinville recorded the voice by using a
“phonautograph” to scratch sound waves onto a sheet of paper covered in
black smoke from an oil lamp. He never intended to play the sounds.
Instead, he archived the recording and patented a method for
understanding sound. Researchers recently unearthed the recording at
the Academy of Sciences (French) in Paris.

Audio historians, recording engineers, and scientists working in conjunction with the informal collaborative group First Sounds
created high-resolution, high-grade scans of Scott’s phonautogram,
converted the images into digital form, and played the sounds on a
computer with a virtual stylus. Then they evened out speed fluctuations
and tweaked the tracks to pull the voice forward.