Here are the ambient sounds in SCP: Containment Breach: Ultimate Edition. The sounds will play at random intervals when the player is in the Entrance Zone.
A little compare and contrast with the Ultimate Edition mod and the vanilla game: • SCP: Containment Breach - EZ Ambience
Here are the following: SFX\Ambient\Zone3
Ambient1 - 0:00
Ambient2 - 0:05
Ambient3 - 0:08
Ambient4 - 0:11
Ambient5 - 0:12
Ambient6 - 0:19
Ambient7 - 0:21
Ambient8 - 0:23
Ambient9 - 0:27
Ambient10 - 0:31
Ambient11 - 0:36
Ambient12 - 0:41
Ambient13 - 0:46
Ambient14 - 0:50
Ambient15 - 0:58
Ambient16 - 0:59
Ambient17 - 1:00
Ambient18 - 1:01
Ambient19 - 1:02
Ambient20 - 1:04
Ambient21 - 1:10
Ambient22 - 1:20
Ambient23 - 1:28
Ambient24 - 1:33