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“A Grammy In Mathematics…”

February 18, 2008

Imagine holding in your hand the only existing live recording of a historically significant musician, Woody Guthrie.  It’s absolutely irreplaceable and it’s incredibly fragile; it’s a wire-recording…

So she (Guthrie’s daughter Nora) was determined to preserve the recording. For the first step, she and a team of engineers transferred it into digital format. It was a hair-raising experience. “The wire was really flimsy,” says Jamie Howarth, a sound engineer on the job. “It was frustratingly, maddeningly fragile.” It snapped over and over, and with every snap, a moment of the recording was lost. And when it didn’t snap, it kinked and snarled.

Wire recorders had lots of problems beyond fragility; the sound quality varied for many reasons.  Fixing that sound quality was a job for… a mathematician! 

The team discovered the many ways that wire makes a lousy material for sound recording. One problem is that wire’s round. When the wire kinked, it would twist out of position and the head would no longer be reading the proper side of the wire. The machine still read the low and medium frequencies, but the very high frequency sounds dropped out—including the signal Howarth used as his foot-beat.

Short developed techniques to interpolate the missing information. “We could actually pick up a hum from the Con Edison power supplies,” Short says. “It’s a pretty nasty noise.” Because that hum was lower frequency, it remained even in the twisted sections. Short also brought in more sophisticated techniques to shift the pitches once the algorithm had identified what needed to be done.

“When it was done, we were all just awed by this recording,” Howarth says. “It was miraculous.” Despite all the difficulties in the process, the wire recording was in many ways surprisingly good.

Click the picture to visit the original article and listen to the before and after-processing clip.  (Thanks to one of my sons for the link)

One of the advantages of an analog recording is that it can be decoded as long as it is intact. But it’s the “intact” part that is a problem.  Digitizing crumbling documents and recordings allows the bits to transcend the atoms.  But one problem with digital content is that the format can change until there’s no way to read it. I wonder how stable our digital media formats are now? 

Categories: Science & Technology
  1. Ted
    February 18, 2008 at 15:30 | #1

    You may have covered this before, but what is Lucas’ goal mathematically?

    Poor academic, rich quant, inventor of the next LZW/MP3 patent, guest starring gig on Numb3rs?

    I am curious what the reasoning looks like from that vantage point. There are of course many reasonable answers—the beauty and elegance of math, fame and renown, easy access to hot chick math groupies. That kind of thing.

  2. Lucas
    February 19, 2008 at 22:43 | #2

    I’m hoping for moderately well-paid academic—most tenure track academics are fairly well paid.  If that fails for some reason, I’ll probably try to get a job at a software company as (ideally) a researcher, or (more realistically) a programmer who works on mathematically-oriented projects.  My area of math is not very closely related to any “hot” areas right now, so I don’t think that a Ph.D. is a get-rich-quick scheme.

    Where are these hot math groupies?

  3. Ted
    February 20, 2008 at 07:53 | #3

    Where are these hot math groupies?

    You said it up above. They hang out at software companies looking for the next stock option boy able to buy them the 4200sq/ft home, pay for private schools, the third car in a two person family, and keep them in Banana Republic clothes.

    But you can find them closer to home if you’re willing to redefine the notion of hotness. I sent one such definition to DOF by email.

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