jabberwock777 said:
Stereo requires not just two signals, but two channels carrying the same sound with positional information added, even if the positional information says it's panned dead center. Left and right channels are required for actual stereo.
Eh. Disagree. Hmmmm.
Well, the "positional information" is not some secret signal that some Dolby engineer throws in there to mystify your aural perceptions. It's just that the signal is louder in one speaker than the other, so it sounds like it is more on that side (typically). I mean, you could also record the same sound from two different microphones that are spaced right and left.... then send the right microphone signal to the right speaker and the left mic signal to the left speaker. This also would be stereo. They are not the "same" signal, though they are similar.
Also there is something about whether the speakers are in phase or not that affects whether the sound comes like it is coming from in-between the speakers, or from the center of the room. You'll know what I mean if you have ever used the calibration DVD for your home theatre and they are checking to make sure you've got the phase set properly. "Video Essentials" I think is the name of it, though there are others.
From:
http://www.m-w.com/
Main Entry: ste·reo·phon·ic
Function: adjective
Etymology: International Scientific Vocabulary
: of, relating to, or constituting sound reproduction involving the use of separated microphones and two transmission channels to achieve the sound separation of a live hearing
Of course, you can have a mono "live hearing", but you know, I'm thinking Webster meant "live" like "strictly acoustic".
I just don't think the two channels have to be carrying the same sound. If you've got one instrument panned all the way to the right... then none of that signal is going to be coming out of the left speaker. But as long as you've got something (that is in some way different) coming out of that other speaker - blam! you've got stereo.