Using 3D mapping, scientists at the Lawrence Berkeley National Laboratory have been able to unlock the audio secrets hidden in a piece of foil from 1878.
In 1877, Edison invented the tinfoil phonograph — one of the earliest audio-recording devices. It worked by translating sound patterns into grooves, which it would transcribe onto a piece of foil. He made his first recording that year — himself reciting "Mary had a Little Lamb" — but, because the foil is so fragile, that recording has since been lost, believed to be destroyed.
That fragility was the problem when it came to playing back a particular piece of foil from 1878, which has been silent for decades, languishing in the Schenectady Museum since being donated in 1978. But a team of scientists led by physicist Carl Haber at the Lawrence Berkeley National Laboratory in Berkeley, California, were able to give it a voice again.
They created a 3D scan of the foil, and then recreated the way the needles would have moved across the grooves, using physical modelling and maths in order to reconstruct the audio.
The resultant recording, which is among the oldest in the world, runs for just over a minute, and consists of a voice reciting nursery rhymes — "Mary had a Little Lamb" and "Old Mother Hubbard" — and laughing, as well as a jaunty tune played on a cornet. It is believed to not be Edison himself, but a political writer named Thomas Mason.
You can listen to the cleaned-up recording below, and read more about the remarkable recovery process on Haber's research site.