Hearing a Master.s Voice

The spools of wire below contain the only known live recording of
the legendary folk singer Woody Guthrie. A mathematician, Kevin
Short, was part of a team that used signal processing techniques
associated with chaotic music compression to recapture the live
performance, which was often completely unintelligible. The modern
techniques employed, instead of resulting in a cold, digital
output, actually retained the original concert.s warmth and depth.
As a result, Short and the team received a Grammy Award for their
remarkable restoration of the recording. To begin the restoration
the wire had to be manually pulled through a playback device and
converted to a digital format. Since the pulling speed wasn.t
constant there was distortion in the sound, frequently quite
considerable. Algorithms corrected for the speed variations and
reconfigured the sound waves to their original shape by using a
background noise with a known frequency as a "clock." This clever
correction also relied on sampling the sound selectively, and
reconstructing and resampling the music between samples.
Mathematics did more than help recreate a performance lost for
almost 60 years: These methods are used to digitize treasured tapes
of audiophiles everywhere. For More Information: "The Grammy in
Mathematics," Julie J. Rehmeyer, Science News Online, February 9,
2008.