doesn't that [phantom center in stereo] illustrate how you can fool spatial hearing to hear sounds from directions and locations here there's no physical sound sources?
The phantom center in stereo is just a matter of the dispersion of the speakers. The overlap in the middle fills in the gap. That isn't a new discrete channel coming from a different direction. It's just putting two channels close enough together that they form a seamless whole.
If that is true then binaural recordings are useless. Why see the trouble of making a binaural recording, if the resulting "headstage" is all in your head anyway? Have you bigshot ever heard binaural recordings?
Yes I've heard binaural recordings, and I do think they are kind of useless for music production.
There are two problems:
1) Binaural recording is extremely limiting and inflexible. Since it demands a single microphone position with a specific pattern of sound, it makes just about all other recording techniques impossible. You can't mix different sound elements together. You can't overdub. You can't adjust balances or EQ. You can't edit it. It's basically tying the hands of the engineers and forcing them to just take a "snapshot" of sound. An engineer's job is to create the sound stage or field or scape or whatever... not to just capture a specific moment and place as a static thing. The inflexibility of binaural is its biggest drawback by far. (I've explained this in more detail in previous posts, so I won't go any further than that here.)
2) Binaural miking techniques can create a startlingly realistic atmosphere or presence. But that isn't the same as direction or location. I'll go into a little more detail about directionality and location.
Direction and Location are primarily communicated to us through visual cues (that musician sitting in front of us). Visual cues are extremely powerful. I got vivid proof of that about ten years ago... I was at a public event with my dog in a carrier. The dog barked furiously inside the bag, then an old man standing a little distance away did a big double take on the dog carrier and gave me an irritated look as if to say "make your dog be quiet!" Then I heard a voice in the distance saying "Hey! No dogs allowed!" and the old man swung around and looked behind to look to the direction the call came from. I looked down at my dog carrier and I could see that my dog was lying down asleep. I looked in the distance where the call had come from and no one was there. That's when I recognized the old man. It was Paul Winchell the ventriloquist. The barking and the yell from the distance had both come from him. But I perceived one as coming from the dog carrier, and the other coming from the opposite direction. Why did I perceive it that way? Because he did big double takes and glared at the direction he wanted me to hear the sound coming from. He was visually tricking me into thinking sound was coming from a different direction than where it actually came from. Visual cues are VERY important to how we hear. I know that doesn't sound intuitive, but it's true.
We also perceive location and direction by moving our head or body in relation to the object we're trying to locate to perceive a difference. The closer the object is, the more difference there is. The more distant, the less difference. We perceive things in front or behind us by moving our ears relative to the sound to figure out which ear it's closest to. Deer do this to discern predators. They cock their head and turn their ears back and forth to locate the direction of a soft footfall or the rustle of a bush in the distance that they can only hear and not see. This is also a very powerful way of discerning direction. Again, it may not seem as important as it actually is. It's so ingrained in us that we don't do it consciously, but we do it every waking hour of our life.
Visual cues and moving the head are both primary direction cues. They are the things we rely upon the most to determine sound location. Neither of these things can be recorded with a single microphone. Visual cues require a visual element to pull off. (Natch!) Head movement can be utilized with multichannel sound. As I explained before the number and placement of the speakers dictates whether sound is one dimensional, two dimensional, or three dimensional. The more speakers you use, the more precise your placement can be. I've been told that the orders of magnitude of preciseness are exponential. Two speakers are better than one. Four are better than two. Eight are better than four... and so on. Atmos is state of the art right now, but it still depends on creating a cube of sound the exact dimensions of your listening room. It can't fool you into perceiving depth larger than your room without using
Secondary Depth Cues. These are less perceptual than they are impressions simulating depth.
Take for instance the call from the distance when I met Paul Winchell... It sounded like it was coming from hundreds of feet away, but it was actually coming from the old man standing in front of me. He was just constricting his vocal cords to restrict the frequency response of his voice to make it sound like a yell coming from a great distance. When that was added to the visual cue, he totally sold it. There's no way I could have perceived that accurately. When you add secondary cues to primary cues you can work wonders. Examples of secondary cues are room reflections, head simulations, volume level, response narrowing, reverberation, etc. You know all about these things. I don't need to explain them to you. Your cross feed operates on these principles as do DSPs, and engineers use them all the time when they are creating a soundscape by mixing.
Now comes the problem with depending on secondary cues alone... If a primary cue conflicts with a secondary cue, it creates confusion and the illusion starts to fall apart. When I listen to binaural recordings, I can hear the realistic ambience, but if I turn my head, it all falls apart. I remember hearing a buzz clipper that was supposed to be behind me. But whenever I moved it would snap from behind me to in front of me, because my ears were expecting that illusion to work with the movement of my head, but it didn't. I could perceive the sound coming from a little distance from my head because it had the proper head simulation going on, but I had no way to determine direction any better than with headphones- one dimensional- just left and right. I suppose if I was strapped into a chair and listened to it enough, I could get used to it enough to like it, but that isn't how I listen to music.
With my 5.1 speaker system, I have both visual and head movement. I can look at a speaker and focus on its output, and then I can locate it in space by moving my head a little bit. If I want to imagine I'm in Notre Dame for an organ recital, it's best to close my eyes and let the secondary cues and head movement create that illusion. At least I have one kind of primary cue. With headphones, I get just secondary cues. Any kind of recording can have secondary cues. Speaker systems are capable of using both kinds of primary cues. That's what sets speakers apart. Cross feed doesn't make headphones sound almost like speakers. It just makes headphones sound better. Speakers have dimension. The more speakers, the more dimension. Put head tracking on headphones with a computer simulation and maybe I can close my eyes and get at least one kind of primary cue. But I haven't tried that myself yet, so I don't know the limitations there. It really doesn't matter because I have a 5.1 speaker system. No need for simulating one. I would love to have Atmos, but unfortunately my room won't work with it.