The idea is simple: Make a high-resolution digital image of a sound recording and develop software to analyze the image and reproduce the effects of a phonograph needle.
Scientists at the Lawrence Berkeley National Laboratory and the Library of Congress have brought the concept to a practical application over the past 10 years, developing a system to digitally recover and preserve rare and damaged recordings without the risk of doing additional damage.
The result is the Image, Reconstruct, Erase Noise, Etc., or IRENE, now being used by the Library of Congress. A version capable of two-dimensional imaging is used for disc recordings with lateral grooves, and three-dimensional imaging is used for cylinders with vertical groove modulation. The 2-D version also works for imaging and playing back optically recorded audio files, such as those on early experimental recordings and on some motion picture soundtracks.
Source: GCN See Also: A race to restore the voices of the past (GCN)