Physicists from the Lawrence Berkeley National Laboratory are using the same methods to search for the elusive Higgs Boson particle and to digitally restore audio recordings from the past. Berkeley Lab signed an agreement with the Library of Congress to digitize the many thousands of early blues or jazz recordings it has in its archives. And the results are spectacular. Compare for example, these two versions of "Good Bye Irene", before and after being optically reconstructed (WAV format, 18 and 19 seconds). This news release describes the method used by the physicists.
"We developed a way to image the grooves in a recording that is similar to measuring tracks in a particle detector," 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.
Their work could ultimately enable the Library of Congress to digitize the thousands of blues, classical, Dixie, jazz, and spoken word recordings in its archives. The mass digitization of these aging discs and cylinders will both preserve the nation's musical history and make it accessible to a wide audience.
||Here is a photograph of Vitaliy Fadeyev (left) and Carl Haber with some of the wax cylinders, and acetate and shellac discs (Credit: Berkeley Lab).|
||And this is an image of a region of the surface of an Edison Blue Amberol cylinder. "The field size is 1 x 0.91 mm and is also acquired with a commericially available laser confocal scanning probe" (Credit: Berkeley Lab).|
How does this work?
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 theorized 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 modeled 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.
The scientists don't want to stop there. They have ambitious plans.
Fadeyev and Haber will advance the study of 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.
In addition to preserving the past, mass digitization gives the public greater access to thousands of old recordings, some so fragile that even the touch of a stylus could damage them.
You can listen to more sound clips before and after correction by going to this page.
And if you're really interested by this method, you can read the technical paper describing this work, "Reconstruction of Mechanically Recorded Sound by Image Processing" (PDF format, 21 pages, 1.21 MB).
Source: Lawrence Berkeley National Laboratory, April 16, 2004, via EurekAlert!