Ok, so this isn't one of those issues where you can't hear anything, or can't hear at least something.
This has to be something with 3D positioning sound issues. I started noticing it during the "Doppelganger" mission when I was heading there. A car passes by me, and judging by the position where the sound was coming from, I looked towards that direction. Nothing there. Then, all of the sudden, I have two Privateers shooting at my back. And then I find the car right behind me. Opposite of the direction the sound came. This is getting really frustrating, as I like to go stealth, and it doesn't really help to have your situational awareness ruined. Please find a fix for this, or I'm not going to play it like I did before this happened.