AH uses mono sounds which are placed to a certain dot according the source. Just as in real life: You hear a knocking on the door, one door, one knuckle i.e. mono. You have two ears that receive the knocking sound and your brain processes that information so that you can tell the direction and distance of the sound.
Think about a tank in front of the tower. You see it, and the sound seems to come from in front of you. Turn your virtual head and the sound moves accordingly from both ears to the one that is closer to the tank. The tank itself isn't moving.
Stereo or multichannel is a way to place monaural sounds in a sound field by amplifying a certain sound in one loudspeaker and dampening it in others. The volume difference in various speakers gives the impression where the sound source lies.