system
Given the following post, respond as if you're commenting on Reddit:
human
Can we and how do we determine if a sound is produced in front or behind us?

Obviously we can tell if a sound is on either side of us, but can we - without visual aid - tell if it’s in front, behind, above or below us? If so, how?
gpt
Something called "spectral cues" comes into play.  Sound interacts with the actual surface of your ear lobes before it gets processed (similar factors in skull shape, nasal passages, etc.).  This changes the timing, resonance, etc. in minute ways but your brain is able to recognize these patterns and use them to help recognize the direction even in the plane between ears.

There's actually a really cool experiment you can do to show this.  Have one person blindfolded and stand in the center of an area.  Have another person stealthily move around and clap from various directions, and have the person point to where they heard the noise come from.  Then, use a soft clay or similar substance (bread dough works) to fill the grooves of their ear lobes without obstructing the ear canal.  Repeat the experiment, and you will find that they sometimes point in the completely wrong direction (especially for positions directly above or below them).  They may also get confused and have no idea where a sound is coming from.