From: jel@sutro.SFSU.EDU (John E. Levine)
Date: Tue, 30 Nov 93 22:47:55 PST
To: newsham@wiliki.eng.hawaii.edu
Subject: soundfile stego
In-Reply-To: <9312010628.AA07814@sutro.SFSU.EDU>
Message-ID: <9312010643.AA07855@sutro.SFSU.EDU>
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>> Also, I am told that humans have a tough time identifying
>> the phase of the frequency components of the sounds they
>> identify.  So one could hide date in the phase relationships
>> among the frequency components of, say, recorded speech.
>
>This sounds interesting.  How about detection,  how will some
>random phase relationships stand out against normal phase of
>various frequencies?

I suspect that the unusual phase relationships would stick
out, to anyone looking at the speech with,say, an oscilliscope.
  Eg, a squarewave would look pretty mangled if you shifted
its component frequencies by some random amount, even though
a human being might not be able to detect the difference between
a squarewave, and a component-frequency shifted squarewave.
  On the other hand, how often does speech over some electronic
medeum actually get analyzed this deeply?