Monday, December 1, 2008, Joint Physics Colloquium, 4:30 PM, 104 Thaw Hall, PITT

Dr. Vitaliy Fadeyev

Santa Cruz Institute for Particle Physics, University of California

"Imaging the Voices of the Past: Using Optical Metrology to Restore Early Recorded Sounds"

Abstract:

For much of recorded sound history, audio information was stored on mechanical media, such as a phonograph disc record or cylinder, through undulations of the surface structure (grooves). The groove shape and position can be reconstructed without mechanical contact using precision optical metrology tools. The surface map thus obtained can be digitally processed to remove noise artifacts due to debris, damage and wear, and to convert the groove positional information into audio data. A few years ago the viability of this approach was demonstrated on a 78 rpm shellac disk using two dimensional image capture and analysis methods and further developments are reported. A three dimensional reconstruction of mechanically recorded sound has been then completed. The surface of the source material, a celluloid cylinder, was scanned using confocal microscopy methods and resulted in a faithful playback of the recorded information. These results are discussed. The approach holds promise for the reconstruction of valuable historical recordings, using full surface information to improve the sound fidelity, and eventually as a means of automated mass preservation. Fast processing is required for the latter application. Methods to accelerate the scan rates and make these techniques practical for use at working archives are discussed. The discussed technique was developed using the tools and methods employed for the ATLAS detector at the LHC.