I have a CD with 3 separate sound clips that I can throw into a small boombox or larger sounds system and hit repeat for multiple hours of ambient noise that automatically increases training difficulty to any scenario.

The first is the crowd noise from a World Cup. A crazy loud thrum of hundreds of thousands of people screaming at the tops of their lungs. Great for riot control/civil support training.

The second is about 10 minutes of crowd noise, followed by several gunshots, an explosion, and then about 10 more minutes of screams and chaos. Great for riot control/civil support training, but also good for react to contact, or other MOUT/Urban training environments.

The third is just the chaos sounds of a war torn city. Screams, yelling, crowd noises, gun fire and explosions in the distance, emergency vehicle sounds. Basically a bunch of randomness to get someone used to the sounds of combat. That and it’s a decent thing to add to nighttime training because Soldiers have to adapt to the idea that bad things are happening “right over there” when they’re trying to sleep.