Anniversary of the oldest-known voice recording

Many people in the United States believe that "Mary Had a Little Lamb" was the first-ever recording of the human voice. But Thomas Edison's device was actually not the first. A Frenchman named Edouard-Leon Scott de Martinville did so, singing "Au Clair de la Lune" in 1857 - 20 years before Edison invented the phonograph. Hosts Carolyn Beeler and Marco Werman explain.