21-02-2009, 10:36 PM
Bulk of recorded sound history the audio information was stored in
mechanical media, such as a phonograph record or wax cylinder, via
undulated surface incisions (grooves). The groovesâ„¢ shape and
position can be reconstructed without mechanical contact by using
precision optical metrology tools. The surface map thus obtained can be
digitally processed further to remove noise artifacts due to damage and
wear, and to convert the groove positional information into audio
format. The viability of this approach was recently demonstrated on a
78 rpm shellac disc using two dimensional image capture and analysis
methods. The present work expands on these results. A three dimensional
reconstruction of mechanically recorded sound is reported. The surface
of the source material, a wax cylinder, was scanned using co focal
microscopy techniques and resulted in a faithful playback of the
recorded information. The approach holds promise for careful
reconstruction of valuable historical recording using full surface
information to improve the sound fidelity, as well as means of
automated mass digitization. Fast processing is required for the latter
application. Methods to accelerate the scan rates, thereby making these
techniques practical for use in working archives, are reported.
