Particle physicists rescue rare vinyl recordings
(New Scientist) Classic audio recordings preserved on a warped and damaged records could yet be rescued for future generations using an optical analysis technique originally developed to keep track of subatomic particles. Many rare vinyl recordings exist in libraries around the world. In the British Library’s National Sound Archive there are more than a million old vinyl records. But even running a needle across some of these old records can damage them severely.
So researchers at Lawrence Berkeley National Laboratory in California, US, adapted a sensitive instrument used to build a colossal particle accelerator as a highly sensitive optical recording method.
“This enabled us to develop a non-contact way to measure delicate records without the need for much operator intervention,” says Vitaliy Fadeyev who developed the technique with colleague Carl Haber. “It also has the potential to digitally reassemble broken discs.”
Precise alignment
During construction of the lab’s five-storey tall ATLAS instrument, which is soon to be used to search for an elusive particle called the Higgs boson, a precise optical system was used to align the silicon detectors used to monitor the trajectory of subatomic particles.
By modifying the instrument and passing it above the grooves used to store audio on vinyl, the researchers were able to visually record their position to an accuracy of a one thousandth of a millimetre.
Furthermore, algorithms used to strip away background noise from particle data proved an effective way to clean up scratches and other flaws on the vinyl. This image of the grooves was then fed into a “virtual” record player to recreate the original sound.
“From a machine imaging point of view, a scratch looks very different from a groove,” Haber says. “So you can tell the computer to just delete the scratches.”
Raw information
Existing methods for restoring old records typically rely on making a recording in the conventional way and then cleaning the audio up on computer afterwards. Haber says the optical method’s high sensitivity preserves far more raw information and therefore produces better quality audio.
One audio restoration expert familiar with the technique says it has already shown real promise. “It’s of great interest,” he told New Scientist.
The researchers have shown that the technique can faithfully restore some extremely rare recordings to their former glory, including the 1950 recording of “Goodnight Irene” by Huddie “Leadbelly” Ledbetter.
The team have released two audio clips (Windows Audio File format) to highlight the difference between the recordings before and after the optical technique was applied.
The work has been carried out in collaboration with the US government’s Library of Congress, which has a huge vinyl catalogue of blues, classical, Dixie, jazz and spoken word recordings.
Mark Roosa, the Director for Preservation at the library, says the undertaking “signals an important new direction for preservation of collections of this type, which we hope will be of benefit to libraries and archives everywhere”.
