It appears we failed to properly explain that mechanic, oops >.<
There's a "sound source" system that completely mimics the behavior of a regular audio source from the Unity engine! Instead of playing audio in your headphones, it visually shows what made the sound, and the general direction it is coming from. For example, an enemy behind or in front of you would make a "noise" that would be around the center of your screen, whilst one to the left or right is in the corresponding sections.
The game is the most basic interpretation of the theme, in which "Silence" is taken literally. No sound, only visuals to help replicate how audio helps you in a videogame (directional awareness)