Here's another: the human ear is phenomenal at determining where in 3d space a sound is coming from. Most animals can only determine direction and can't really place a sound vertically. Watch what your cat or dog does when they're looking for the source of a noise, it takes them a lot longer.
I've heard that this is the reason dogs will tilt their head when looking curiously at something, as this lets them better differentiate sound positions vertically.
iirc it's because human ears are slightly offset to each other vertically. The brain then calculates the time difference it takes each ear to hear it. Basically triangulation.
I've never liked this explanation because if that was all there was to it, it would still only localize to a slanted line in front of us.
Say for example the right ear is higher (I tried finding which one normally is, but couldn't find a good answer) in this case it would not be feasible without other clues to tell the difference between a sound being higher up and slightly to the left, or lower and slightly to the right. It's not a significantly different situation from the ears being the same height.
In reality there are other clues, largely based on the shape of our ears slightly changing the sound in learned ways based on the angle it comes from.