What is that sound? (Destiny)

by Ragashingo , Official DBO Cryptarch, Monday, December 01, 2014, 13:10 (3441 days ago)

There is a strange, mechanical sound that plays during the Venus Strike right after you enter the rock tunnel that leads to the cliffside where the pile of Vex teleport towards you just before the boss battle. The sound only seems to happen for you personally when you cross a certain point. Directionally it's coming from behind and above you.

Does anybody have any idea what is making the sound?