Harmony In Extremis

Like every game or televised program, there is a musical score to go along with it.  The music, or soundtrack, is an essential part of games and movies.  Sound and music are a huge part of what makes the certain piece of entertainment you are playing / viewing complete, especially when it comes to the horror genre.  Other than L4D, the two biggest games that I can think of as examples for this are Silent Hill and Resident Evil.  I have played Silent Hill 2 with and without sound and it is terrifying with sound, but when it's off the game suddenly become a whole lot less creepy, same with Resident Evil 4.  Anyways, Left 4 Dead's soundtrack is all composed by Mike Morasky.  The way that the sound and music is directed in Left 4 Dead is the same as I just explained for Silent Hill 2 and Resident Evil 4.  The structure style of the songs and how they're used are similar to that of a movie - certain cues will often be repeated throughout the soundtracks, like a recognizable theme for the game.  Various songs will play when something happens to your character or when you reach a certain point in a level.  Here is a link I found to all of the songs in the game (through youtube):  http://left4dead.wikia.com/wiki/Left_4_Dead_Soundtrack