It depends on your character’s orientation with respect to the audio source (the npc who’s talking).
So for example, if an npc is saying something, while you’re facing him/her directly you may not hear anything, but if you position your character in such a way that the npc is “near” your speaker, then you can hear them talk. So as you rotate your camera around, you will hear the voice fading in and out.
This has been going on since release and I thought would be one of the first things to get fixed but it’s still happening.
Anyone else experiencing this?