The two main soundtracks in Garrys Mod Zombie Survival gamemode.
0:00 Zombie (Main Theme) 3:08 Human
The first is "Zombie" which plays when the zombie team gets a hold on the game round. The second is called "Human" which plays when the human team is prominent.
The audio is split up dynamically in the gamemode. The songs are two whole tracks but are multiple sound files. This is a compilation of the files to sound as authentic as possible to the gameplay experience.