Audio log

Audio Logs are sound files found at various types of data terminals in Halo 3: ODST. They tell "Sadie's Story", about an African girl called Sadie Endesha during the invasion of Earth in October 20, 2552. Each log is accompanied by a "movie" of images.

Unlocking Audio Logs will also unlock Supply Caches scattered throughout the level Mombasa Streets. There are 30 logs in total. 29 of them can be found in Mombasa Streets while number 30 can only be found after acquiring the other 29. Number 30 can be found by following the police officer in Data Hive. When all 30 logs are found, the achievement Audiophile is unlocked.

Trivia
The audio logs have some references to Dante's Inferno.
 * There are 9 Circles of audio logs, correlating with the 9 circles of hell in the poem.
 * Circle 1: Limbo
 * This is the start of the story. Everyone around Sadie feels safe on Earth until the Covenant come, then they realize they are in hell (which Sadie states).
 * Circle 2: Lust
 * Kinsler is overcome with lust, even though the world is about to be destroyed around him.
 * Circle 3: Gluttony
 * This circle contains Jonas, who is a very large butcher handing out food.
 * Circle 4: Avarice (theft)
 * This circle is centered around the casino district, where many people are looting the casinos.
 * Circle 5: Wrath and Sloth
 * Sadie and Mike attempt to cross the bridge back towards the ONI building, only to be stopped by Kinsler (fallen angel guarding the gates.) An Olifant sent by Vergil (heaven sent angel) let's them pass safely.
 * Circle 6: Heresy
 * This circle is centered around Vergil the Huragok, who goes against the Covenant's faith and helps the humans. This is also where Tom the salesman reveals Sadie's position.
 * Circle 7: Violence
 * This circle is centered around a deranged officer who kills people inside the police station. He is eventually killed by a SWAT team.
 * Circle 8: Fraud
 * There are numerous fraud allusions, including Sadie faking she has a gun to have Vergil turned back on, and the Public Service Announcer who lies to give hope.
 * Circle 9: Treason
 * Kinsler returns for the third time, tricking Sadie in joining him by threatening her father. Even though she agrees to go with him, Kinsler kills her father. This also shows the killing of civilians by the police, who swore to protect them.
 * The thirtieth audio log is found in Dr. Endesha's office on the 9th sub-level of Data Hive. The frozen area where you find the 30th audio log may be a reference to Cocytus, the 9th level of hell.
 * Vergil correlates to Virgil, who led Dante through the Nine Levels of Hell, just as Vergil leads Sadie, and then the Rookie, through New Mombasa.
 * Around New Mombasa, when there are civilian and police cars with their alarms/sirens blaring, street signs telling you to go somewhere, street blockers lifting or going down, this signals that there is an Audio Log nearby. Once the Audio Log is found, the alarm/siren, signs, and street blockers will stop and go back to normal.
 * The thirtieth Audio Log can be collected an infinite number of times, because the police officer will always continue into that room, even if you've already collected all of the audio logs before, on the same profile, with the same saved data. Note: This will not apply if you have not collected the 29 Audio Logs in the level Mombasa Streets.
 * The task of collecting these audio logs marks the similarity of finding the Terminal from Halo 3 which also tells a story.

Internal

 * Sadie's Story
 * Axons

External

 * GamesRadar's Audio Logs/Sadie's Story Walkthrough
 * An overview map of New Mombasa and locations of Audio Logs
 * An overview map of all the audio logs with in-depth videos and locations provided by Achievement Hunter from RoosterTeeth
 * Overiew map of New Mombasa and Audio Logs provided by NextgenWalkthroughs
 * Audio Log Recordings by R3b3L iNk