What was the first sound-recording device called?

The first sound-recording device was called the phonautograph.

French inventor Édouard-Léon Scott de Martinville patented the phonautograph in 1857. The device used a horn, vibrating membrane, stylus, and soot-coated surface to trace sound vibrations visually.

Unlike a phonograph, the phonautograph could not reproduce the sounds it recorded. It was designed primarily to study acoustic waveforms and create visual records called phonautograms.

The phonograph, developed by Thomas Edison in 1877, came later and could both record and play back sound. In 2008, researchers digitally reconstructed audio from several surviving phonautograms, including an 1860 recording of “Au Clair de la Lune.”