(resent) At 11:44 AM 6/13/03 -0400, Peter Wayner wrote:

At 9:27 AM +0200 6/13/03, Thomas Shaddack wrote:

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See also something about computer-generated music: http://brainop.media.mit.edu/online/net-music/net-instrument/Thesis.html

...

I'm told someone is trying to encode information by ordering the musical notes played in a chord with a Midi synthesizer. It's possible to hide information in the order of a set using a technique like this:

http://www.wayner.org/books/discrypt2/sorted.php

That's cute --there's no acoustic difference. There are also methods which produce nearly imperceptible differences --you can adjust the millisecond-scale timings, or the dynamics. Since these will vary with each performer's rendition anyway, they're fairly stealthy.