Halo: The Master Chief Collection - Halo 2 - Siege of Ivory Tower - Halo 2: Listen to a hidden music cue in Halo 2. This achievement is fairly easy to unlock.
On the map Ivory Tower, the beginning steps aren't confirmed but I followed them and my achievement popped. First make sure you have your crouch setting to toggle crouch NOT hold for crouch.
When you spawn head to the bottom area and grab the energy sword. Walk over to the metal door, crouch and wedge yourself in the left corner.
Now you sit there and wait.
For me it only took about 2-3 minutes of crouching in the corner before the achievement pops. Wait patiently and your achievement should pop! Enjoy!