Audio log (Halo 3: ODST)
From Halopedia, the Halo wiki
Audio Logs are sound files found at data terminals in Halo 3: ODST. They tell the story about a Kenyan girl called Sadie Endesha during the invasion of Earth in October 20, 2552. Unlocking Audio Logs will also unlock Supply Caches scattered trough the level Mombasa Streets. There are four Halo 3: ODST Achievements that require you to uncover a particular amount of Audio Logs in order to be unlocked[1][2][3][4].
