The BBC News recently reported that U.S. Scientists at the Lawrence Berkeley National Laboratory (LBNL) in California have retrieved a sound recording of a human voice made by Parisian inventor, Edouard-Leon Scott de Martinville on April 9, 1860. That's well over a decade prior to the phonograph of Thomas Edison singing a children's song in 1877, previously thought to be the oldest known audio recording.
The 10 second sound clip of a woman singing the French folk song "Au Clair de la Lune" was originally recorded on paper by a phonautograph, a device invented by de Martinville. His hope was to create a visual representation of sound waves. The paper was covered in soot from a burning oil lamp, and then lines were scratched into the soot by a needle moved by a diaphragm that responded to the sound. Interestingly, the recordings was never intended to be played. It wasn't until scientists were able to use a "virtual stylus" to read the lines of high-resolution digital scans of the paper that the woman's voice came back to life.
So that prompts the question: if you could find an old recording of one of your ancestor's who would it be, and what do you imagine they would be saying or singing?