Easy to Overlook Achievement in Halo: The Master Chief Collection

This achievement can be done in a custom match on your own, or in Firefight.

On nearly every Multiplayer/Firefight map, there are very specific areas that will trigger hidden UNSC radio chatter. For the purposes of this achievement, the easiest way to get this done is to load up a custom match on Overlook. Once the game begins, make your way to the top floor of the large two-story building (Barn High); it's located across the blue water drums. Here, you should be able to trigger the radio chatter and unlock the achievement.