Sound recordings that hadn't been heard since they were first made by Alexander Graham Bell and others in the 1880s were played publicly Tuesday at the Library of Congress in Washington, D.C.
The sounds captured in the collection include recited verse, sounds such as trilling and basic spoken information such as the date.
The recordings — long stored at the Smithsonian Institution — were made on cylinders and discs of varying design. The Library of Congress teamed up with the Lawrence Berkeley National Laboratory to decode the recordings. The AP describes the process:
"Many recordings are fragile, and until recently it had not been possible to listen to them without damaging the discs or cylinders, the news release said. So far, six discs have been successfully submitted to the sound recovery process, which creates a high-resolution digital map of the disc or cylinder. The map is processed to remove scratches and skips, and software reproduces the audio content and produces a standard digital sound file."
More detailed information on how the maps are made can be found on the Lawrence Berkeley National Laboratory's website. You can actually listen to some of the recovered sound on another page at the same site.