Yes, but it wouldn't save any bandwidth, so it would still be at least twice
as expensive as regular telephony, with no discernable advantage to the vast
majority of paying customers. There are plenty of services set aside for
transmitting stereo audio from place to place, but telephony ain't one of
Not using standard multiplexing/demultiplexing technology. I suppose if you
had enough specific information about the original audio environment, and
enough computing power, you could theoretically use holographic-like
techniques to partially reconstruct a 3D sound image from a mono recording.
But if you're talking about recreating two discrete, statistically unrelated
channels that had been previously summed into one, the answer is not by any
means I'm aware of.
Of course, I read recently that Stephen Hawking is now postulating that
information may be read using quantum mechanical techniques, from matter
that has fallen into black holes, so perhaps I'm just not trying hard
You can sometimes synthesize a sort of "surround sound illusion" using phase
information between the two stereo channels, but that's quite different from
restoring actual surround channel information. If you need true surround
sound, you need to record, store and reproduce the actual channels.
Information theory is quite specific on the bandwidth required for each
channel. There's no such thing as a free lunch.
It's true that properly recorded stereo sound contains spatial information.
But in that case, the two stereo speakers or stereo headphones are quite
sufficient to "decode" a 3D image. You don't need a 5.1 decoder. In fact,
binaural sound can be quite stunning. Binaural doesn't sound good over
speakers, though. See http://www.binaural.com/ or http://www.noogenesis.com/binaural/binaural.html or just Google "binaural".