Thanks for putting up the OP, I'm finding this fascinating.
While the fixed distance is correct, if zi hear a constant noise I can move my head, and the brain creates some kind of map based on that?
I think if you heard a noise and the sound was directly ahead the angle between your ears would be 90° (i.e. draw a line between these two ear dots and the sound starts at the top in the middle. .|.If you moved your head the ears would move from left to right you'd find the angles changing from /to \ and back again.So if you kept moving your head you'd have these /|\That would give a good sense of where the sound was coming from, but not how high or low it was.
If you rotated your head (/ears) the angle would change from 90° to a different angle and if you rotated your head so your ears were vertically lined up like this ÷ then you'd know the sound was so far above you or below you like this '!' .(subject to correction from Jeremyp).
So, I think if you rotated your head it could change the angles your ears/ brain was receiving the sound. (There are times I think of trying to draw this 'diagrams' but they are in text, so I hope it isn't too badly drawn.)
Di we get onto bats soon?
It's bats and dolphins, iirc? Dolphins use SONAR not just to detect their prey but as a stun weapon. I think they're all (bats & dolphins) creating their own sounds and using the echos as part of a detection tool.