Eagleboy, I would consider our hearing EXTREMELY directional for most of the audible spectrum, just that our sensitivity to volume is a factor that will easily limit it.
Well, I believe our spatial hearing is accurate to ~5 degrees, but some of that is also due to head movement - something that is not available to us through headphone use.
However, we do have spatial hearing - not as good as other animals, but we do have it available to us, and it is far from terrible.
That was a decent read. Like you said, mainly the beginning. I still don't know if I agree with them about the tree falling in the forest though . Afterall, "sound" is merely perception of energy, and if, like they say, no one is there to perceive anything, wouldn't there just be energy, and not sound?
Yea, like you said, some of our ability to detect direction does come from head movement, which definitely isn't available in headphones. I think that's why headphones, especially 5.1, have a huge job to accomplish. They have to attempt to recreate an accurate soundfield without relying on our ability to vary our ears' position to the speaker. I don't think the 5.1 cans are up to it yet! (though I would like to listen to the $800-900 ones)