Q+A CENTER

Lawrence Berkeley National Laboratory (Berkeley, CA)
(Nominated by Kyle Voosen, National Instruments Corporation, Austin, TX)

The Challenge:

The difficulty in recovering recorded audio from legacy, mechanical sound carriers such as phonograph records and “Edison” wax cylinders is self-evident. Numerous historical recordings, many considered extremely fragile, are held by major repositories across the country and around the World. Preservation archivists would like to reclaim soundtracks without causing (further) damage to the original media. To permit public and scholarly access, comprehensive restoration of these collections is highly desirable.

The Solution:

By applying two- or three-dimensional imaging, it is possible to generate high resolution digital maps of the entire surface of a sound carrier. Images, so created, can be processed to remove debris and lessen the destructive effects of time while improving audio fidelity. A virtual stylus then recovers the sound. For large-scale digitization efforts, recovery may be automated through computer-driven image acquisition, processing and motion control. An imaging workstation, dubbed IRENE (Image, Reconstruct, Erase Noise, Etc), which integrates these methods is under construction.

Two-dimensional imaging serves records that have a groove which undulates laterally in the plane of the disc. Optical line-scanning, at seven-to-ten times magnification, affords sufficient resolution to measure the groove, for example, in 78-revolutions per minute shellac and lacquer records. Three-dimensional imaging, accomplished with a color-coded confocal scanning probe, profiles the surface when the groove ripples vertically as with Edison cylinders.

The Tools Used:

• Aerotech (Pittsburgh, PA) and Newport (Irvine, CA) translation stages, motion controllers and drivers
• Dalsa (Waterloo, Ontario, Canada) Piranha2 line-scan camera
• EXFO (Vanier, Québec, Canada) X-Cite 120 illumination system
• Keyence (Woodcliff Lake, NJ) LK-G157 Series laser displacement sensor
• National Instruments Camera Link PCI-1428
• National Instruments LabVIEW and Measurement Studio Vision Development Module
• Navitar (Rochester, NY) zoom lenses
• Société de Thermométrie Industrielle et Laboratoire (Dammarie les Lys, France) color-coded confocal probe

The Difference It Made:

These imaging methods preserved “lost” or at-risk recordings and facilitated access to historical collections. The value was illustrated by a selection of applications: for the Library of Congress (Washington, DC), an IRENE workstation enabled mass digitization of extensive holdings which covered a variety of formats including shellac, cellulose acetate and nitrate, aluminum and metal stampers. For the US National Archives and Records Administration (College Park, MD), Lawrence Berkeley National Laboratory scientists studied sound recovery from damaged plastic dictation belts, integral to US Presidential history. And, wax cylinders which were recorded at the Jack London Ranch (Glen Ellen, CA) were restored for California’s Department of Parks and Recreation (Sacramento).