The alarm tone is an essential component of the Neon Bunker's defense system. It's a piercing, ear-piercing siren that alerts everyone of impending doom, unless it's just the pizza delivery guy, in which case it's probably just a drill.
There are three types of alarm tones to choose from:
For more information on how to customize your alarm tones, see 3.3.2: Customization.
Customize your alarm tones