Air raid siren [10 hours]
by Kipper
0:39 - 2,992,518 views

Yes, yes, there's an explosion at the end ;)

The title used to be 'Nuclear siren [10 hours]' but that was incorrect, hence the picture.

YOU WON'T HAVE ANOTHER CHANCE
by Squickke
1:50 - 47,311 views

Y͇̮͖̜̟̤͕̓͒̀̎̅̒͑̚̕ͅO̶̬̪̝̺̖͉ͪͥU̸̻̰̱̙̯̅ͭ̕ ̣̩̖̽͂͐̒̊̆͊͝C̬͖̹̬̱͈̿͐̍ͧ̌̈̎͐O̷͒̽̏̈́̀̚͏̖̮̞̫̯̝͈U̶͚̖͕̻̘̞͈͎͖ͤ̽̄͝L̵̝̹͖̗̲̲͙̗ͪͦ̒̉D̢̙̖̹̮̻͋ͧ̀ ̶̧̗̬̫͍̲͆ͮ̂͌ͅͅH̵̶͉̟̅͆̇̎A͆͋̃̑̾̾̆҉̡̖̹͍̳̥̼͖̪V̮̩͓͈̣͚̹̏ͤͣ̑ͭ̎̊̊Ẽ̷͈̣̔̽̎͗̀̈̐͞ ̦̱̘̉̓̓̔͝͞P̪͇̪̺̘̤͉̆R̢̠̠ͦ̿́̚Eͯ́͛͐̆͏̨̡̳̖V͓͍̹͔̦͙̖̘ͭͪ͗ͩ̇ͫͦ̚Ȩ̙̪͖͙́̾͡Ń̟͙͉̗̤̣̗̦̓͘̕͜T̢̥̰͚͈̓ͦ͗ͣ͛̑͌̓͞Ė̻̺̞̮̇͛̆̒̇̕͡Ḍ͉ͣ͋̐̋͢͠͝ ̼͛ͪ͂͐́ͤT̢̔͛̃ͧͫ̒ͥ̽҉̩͍͓̦̥̼͖̯H̷̨̤̻̿ͭ̾͋̄ͪ̓̚͠I̷̼͕̟͙͕̝̼̼̎̈S̪̹̲̗͓̲̄̋͗̉̃̿͊

Real Gun Sounds - What A Firefight Should Sound Like
by LuvDemSoundz
3:12 - 620,649 views

Check out my channel for other videos that you may like.

Download the audio - http://www.mediafire.com/download/yjhih3549xvfj3d/Firefight_Remastered_High_Quality.mp3

A good example of how a real life Firefight would sound like. For those who want to make accurate representations.

I took this from a pretty good quality video. It's still not exactly like real life, hell 'most' of the audio from Firefight or Shooting videos in general are almost nothing like real life. The audio is usually either muffled or distorted. Or may just have poor sound quality in general.
One of the more common things I noticed in most Firefight videos is the lack of echo on the weapons. In real life, the echo is not as powerful or as loud as the "initial bang" but it is also very hearable. It doesn't matter what kind of location it is, as long as there is some sort of surroundings, an echo will be there.

Guns are Loud, Metallic, Dynamic (A loud screaming bang)
When people say Loud, they don't mean like lawnmower loud, it's ear shattering loud. Even from a large distance, they're still fairly loud.
It's "metallic" I can't explain in detail why, they just are.
Very dynamic... I've had people try to argue with me, comparing the dynamics of an explosion to voice or instruments. The power, loudness, and frequency of the sounds are not the same. There's more than just reverb to the dynamics, you can feel and hear the sound bouncing off the world. The sound will change up depending on the angles you hear it from and its surroundings; try this video for an example http://www.youtube.com/watch?v=vXHGAXqFkz4

This is just for the ignorant gamers and film artist who don't know what they actually sound like... Because people are easily fooled thinking "Sounding Cool = Real". If you want an easy real life comparison to how guns may sound, pay attention to fireworks. All a gunshot, cannon, explosion... all it is, is a loud initial bang with an echo. And it becomes louder with pitch differences depending on the caliber and how powerful the weapon is.

Distant Gunfire;
I'm not math savvy, so I could be wrong on the geometry. I'll give my description on gunshot perspectives, based upon what I've commonly heard from real life. From a close perspective, guns are more "high pitched." With large calibers, guns don't start to sound "boomy" until you hear it from a small distance, commonly about 50-400yds, it becomes more muffled the further it is, and depends on how loud the gun is. It doesn't start sounding more like a "thud" until you hear it from a large distance, commonly 700-2000yds. Small calibers usually don't sound "boomy" but are always a "pop/bang" and make a quicker transition to a "thud" sound compared to larger calibers at certain distances. And yes for any gun the echo is also still hearable at ANY distance. It just becomes more muffled like the bang would be.
The Ambient (as in extremely large distance, I.E. miles) perspective is confusing to me a bit. At some points it would sound like a muffled version of the close perspective, and other times it would sound like muffled versions of a distant perspective. Idk, it's just what I've heard from Fort Bragg. Like you mostly hear cannons that would rattle your house which commonly sounds like a dry "VOOM" sound, and then sometimes you would hear a heavy thud and then an echo. It could be taking account to the angles the sound is coming from plus the density (dry/moist) in the air.

In this video/audio in particular, the mic on video to catch the audio has a broad range so it picks up echo very well, even the distant echoes. That's common for some microphones to pick up the echo to be loud as, even sometimes louder than the initial bang. (No, distant gunfire is not "feint pops" in response to what I've read on a forum. That's just the mic range picking up more feedback on the echo than the distant bang.) It's also common for microphones to pick up distant perspective gunfire to be as loud as close perspective gunfire, seeing as how mics have decibel and response ranges and all that, and distant gunfire is also pretty loud. Some mics can pick up the authenticity of the sound, but of course the loudness field would be brought to a certain degree, and it ranges from different mics to where many mics would either muffle the authenticity of the sound or distort it.
The audio on this video is picked up very well, better than every other Firefight video/audio I've heard so far. Of course it isn't perfect like real life, but this video DOES give the best example of how chaotic a real battlefield would be authentically, especially in an urban surrounding.