aural cryptography

[John Kelsey]

Guys,

I was re-reading the original visual cryptography paper last night, and had 
an odd thought: Why couldn't we do something similar with sounds?  The 
human ear/brain is pretty good at pulling patterns out of noise; would it 
be possible to randomly embed half of a low-quality voice channel in each 
of two sound channels, so that they didn't sound obviously bad apart, but 
when played at the same time, would allow the listener to hear a spoken 
message pretty clearly?

It seems like you could even do some pretty weird things with this, like 
embedding the signal in four or five sound channels, or embedding them in 
such a way that the speakers on the different channels had to be a certain 
distance apart for the embedding to work.

So my questions are:

a.  Is this really possible?  Or am I missing something?

b.  Has this been done in the open literature?  (It seems like the sort of 
thing that would have been really useful for, say, radio broadcasts that 
were intended to be received by spies.)

Thanks,

--John Kelsey, kelsey.j at ix.netcom.com



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