Sound waves, she doesn't need to see people, she just moves in general directions and listens for the Scream to bounce off the survivors, then she moves towards them, also she uses the sound of her fellow ZEDs to conduct movement, and if she's alone she listens for Gunshots and any distinct sounds that my indicate your location.
Ok she looks uber ugly in this pic, she looks better in game lol. me and these dudes today where talking about wich was hotter, stalker or siren, I picked siren, but now this concepte is well. Scarying me
What the-
[link]
(it's a some gameplay of the commando class)