Well, long time posted but as admin refered it today, I'm gonna give my 2 cents about human sounds localization. Dunk was the closest to the truth about it btw
First talk about general human ears capacity. Our ears got 1 special system ( if interested pm me) to recognize the frequency of the sound. It then send the input to brain, roughly each frequency for 20Hz to 20KHz is coded by one pack of neurons, so when they activate the brain know wich frequency it hears.
Now, how do we know where the sound come from?
Split possible origin into 2 main cat. : the ones that comes from vertical plan, and the ones that comes from the horizontal one.
First about the vertical, as is it the easiest to explain : we don't know.
The accepted theory until better comes to mind is that vertical sounds reflects on the external part of the ear, and brain can notice the difference between direct and reflected sound. We get to this theory by noticing that ppl who don't have external ears ( because they get burn or something else) can't detect origin of vertical source' sounds. You can reproduce it by puting a tube in your ear ( take care not to hurt)
Now about horizontal. 2 category of sounds (roughly) : high (2k=>20kHz), and low frequencies (20=>2kHz).
For the low frequency ones, brain detect the time between a specific phase of the sound, and so can tell where it comes from. As for low frequency the wave length is larger than head we never got problem to localize short low frequency sounds this way. But what about continous sounds ? Ofc, you can't tell wich ear hear it first as it is continous. Here the brain detects the delay between one of the phase of the sound.
For the high frequency ones, this obviously won't work, as the wave length is by far shorter than head. But high frequency sounds find head as an obstacle and so will reflect on it. Result is that the intensity is different between each ear, and so you can detect the origin of the sound. This works for both short and continous sound.
Maximun horizontal resolution is 2°, means that brain can detect interaural delay of 0,011ms ( !!!)
The interraural delay for a sound that come from side of the head is ~0,6ms.
The world champion of interraural delay analysing is the bat, wich can detect delay of 0,00001ms ( no typo here : it's really 10^-8 sec). Scientist wonder how they do so, as the signal length sends to brain is min 1ms.