Goodnight Irene

Berkeley Lab physicists have developed a new way to digitally restore and preserve audio recordings borrowing from techniques used to study subatomic particles.

The 1995 discovery of the top quark and singer Marian Anderson’s 1947 rendition of Nobody Knows the Trouble I’ve Seen may seem unrelated.

But through an interagency agreement with the Library of Congress, the same technology used to study subatomic particles is helping to restore and preserve the sounds of yesteryear.

The collaboration, which is rooted in a February 23rd agreement between the Library of Congress and Berkeley Lab to conduct media preservation research, takes advantage of Berkeley Lab’s decades of experience developing ways to analyse the flood of data generated by high energy physics experiments.

This work, conducted at accelerators located at Fermilab and the European Centre for Particle Physics in Geneva, requires the ability to image the tracks made by elementary particles as they hit detectors, and find these tracks amid a jumble of meaningless noise.

“We thought these methods, which demand pattern recognition and noise suppression, could also analyse the grooved shapes in mechanical recordings,” says Carl Haber, a senior scientist in Lawrence Berkeley National Laboratory’s Physics Division who developed the technology along with fellow Physics Division scientist Vitaliy Fadeyev.

To test their hunch, Fadeyev and Haber turned to a precision optical metrology system used by Berkeley Lab physicists to inspect silicon detectors destined for the upcoming ATLAS experiment, which will search for a theorised but never observed particle called the Higgs Boson.

Instead of measuring silicon detectors, however, they programmed the system to map the undulating grooves etched in shellac phonograph discs. The images were then processed to remove scratches and blemishes, and modelled to determine how a stylus courses through the undulations. Lastly, the stylus motion was converted to a digital sound format.

The result is a digital reproduction of a mechanical recording, with each wiggle, bump and ridge in the recording’s grooves faithfully captured, and each scratch ironed out. In this way, The Weavers’ 1950 rendition of the classic Huddie Ledbetter (Leadbelly) song, Goodnight Irene, is closely mirrored – minus the hisses, pops, and scratches. The same goes for Nobody Knows the Trouble I’ve Seen. The nearly 60-year-old mechanical recording sounds worn and scratchy, but the digital rendition rings clear, just as Anderson sang it in 1947.

Next, Fadeyev and Haber will study ways to recover damaged and worn cylinders, as well as study the entire three-dimensional profile of a disc’s grooves. Although still under development, the technology could eventually give the Library’s staff a better method to restore some of the 500,000 items it provides preservation treatments to each year, from a collection of nearly 128 million items in all formats.

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