The Smithsonian National Museum of American History is currently holding a few hundred of the earliest recordings in existence. Some recordings were attempted on glass, beeswax, and even rubber while attempting to find the appropriate medium to capture audio during experimentation. The audio recovery process has been a collaborative effort between the Lawrence Berkeley National Laboratory, the Library of Congress and the Smithsonian. Here are a few recordings recovered:
Read and hear more here.
Before Edison invented the phonograph in 1877, Edouard-Leon Scott de Martinville invented the phonautograph which was designed only to record sounds but not to play them back: