[VLM]

A listener on night shift guard duty from a more ancient or more naturalistic culture would perceive it as spirits trying to send him a message (probably just his subconscious working something out, but whatever it doesn't matter) so he's listening really close to the spirits muttering and then "snap", oh foul words, that was a real sound from a real hungry lion, sound the alarm.

Meanwhile people who hear nothing in the wind get bored, fall asleep, and become snack for hungry lion.

This is ignoring the second order effects of most of the voices are probably your subconscious working something out of your system that needed working out, so you'll be a more well adjusted caveman if your PTSD is worked out because of something you heard the spirits tell you on the wind, than if its all bottled up.