Okay, I was working on the "audio files" for the game. There are 30 of them. 29 of them are in "Mombasa Streets", while the last one is on "Data Hive". I just got the achievement for getting 15/30 audio logs.
For anyone doing this achievement! Listen up! You have to do this on solo campaign (any difficulty) and NOT co-op. This is because in solo, you can save your game and quit so you can load up data hive. If you do co-op you can only leave the game and it will not save the audio files, making you do it all again!
I am so fucking pissed! I spent the last 2 hours trying to get the endure achievement. We were at the 3rd set; 5th round; and 3 wave. One of the guys had to talk to his mom or something for what he said would be for only 2 minutes. We all get screwed from the brutes with gravity hammers and we lost all our lives....He's been gone for over 20 minutes! > And he was one of our best players! We could've beaten the achievement by now!