As with all titles on the Xbox 360, "Halo 3" fully supports 5.1 surround sound audio. In the game, there are over 50,000 pieces of audio, with nearly 40,000 of those being NPC dialogue. This is far more than in either of the preceding "Halo" titles; "Halo 2" had over 15,000 pieces of dialogue. The AI controlling this dialogue is designed to ensure the exchanges flow naturally and convincingly. Separate recordings were made for nearby and distant gunfire to make for a more believable sound experience in the public beta, and the finished game uses Waves Audio plugins to modify dialog and other audio in-game depending on conditions. Distant gunfire sounds, which may first seem like pre-recorded ambient sound, may often be the result of an actual firefight happening elsewhere in the game.