PMC AI and Regular AI Audio Detection Range – Is true Stealth Even Possible?

No matter how slow I sneak up to a PMC guarded COB, if I get within maybe 10 feet, even with a fence between us, they get alerted. I am crouch walking the whole time, moving super slow.

Is this a side effect of them wearing amplified ear protection or something?

Same issue with regular AI only I can get a little closer. If I get within 4 or 5 feet, they always turn or react. Is it just not possible to fully sneak up and physically touch an AI before they notice you?

I always end up needed to run at them at the last minute.

anyone know if true stealth and knife mechanics will eventually going to be fully implemented?