Alexander Graham Bell, the man widely credited with inventing the telephone as we know it (though there is a longstanding debate over who actually was first), can be heard again today, some 128 years after he recorded himself counting and speaking in his laboratory in Washington, DC, saying: "In witness whereof, hear my voice, Alexander Graham Bell." The historic lost audio file — the first recording of Bell's voice — was retrieved by several researchers around the country using a technique developed at the Lawrence Berkeley National Laboratory.

Bell's audio recording was made on an old experimental wax disk that he later donated to the Smithsonian Institution's collection, but it was deemed "unplayable" due to its antiquated technology. Researchers weren't sure what device was used to play it back or if it was pristine enough to even reproduce the original sounds.

"In witness whereof, hear my voice, Alexander Graham Bell."

But starting in 2011, researchers at the Library of Congress began using audio recovery technology created by two Berkeley researchers that had been successful at recovering other pieces of audio history, including a tinfoil record made by Thomas Edison and an 1860 recording dubbed the "earliest" in history. The Berkeley method, which was based on particle physics equipment, relies on taking high-resolution digital images of the surface of a physical audio recording medium, such as Bell's wax disc, then running an analysis to rebuild the areas of the recording that are damaged. The result this time: the first playable record of Bell's voice ever obtained in history. Hear it below for yourself in the YouTube video above and view a transcript Bell wrote here.