It's not all about the eyes though, the ears are plenty effective at establishing locations and movement direction.
I made a quick little encounter with 2 squads, 1 opfor and 1 blufor set to search and destroy and both headed towards the same intersection. Their eyes work nicely when they can see contact, aim fire and hit. However, their behavior in establishing a threat axis and using the ears to located enemies or dangers that are not insight leaves a little to be desired.
http://www.youtube.com/watch?v=lM0BQJcZzaU
Encounter happens around 40 seconds into the video.