Expected: AI in non-combat state will immediately spring into action when gunshots are heard. They will hear sonic cracks from rounds passing close by.
Observed: When shots are fired at any range, AI will remain motionless for 4-6 seconds, before suddenly becoming alert and active. Unless the bullets actually strike a team member, or impact right in front of their faces, they will downright ignore the gunfire until an arbitrary timer counts down. This makes them look incredibly stupid, robotic, and gives the player an unfair opportunity to make several shots on unaware targets. Furthermore, the AI do not respond to sonic cracks, only bullets hitting dirt or solid objects. This also privileges the player.