This sound is from Labor Engine - Judgment of Carrion Soundboard

In another optional mission, the player has to guide a "labor engine" to the loading bay, while being guided by a cloaked vox recording, alerting the player when the Tyranids are coming. If the engine is safely transported to the loading bay, the player must then defend it against waves of Tyranid attacks. If it stayed intact by the end of the mission, all the "cargo" is safely transported and the player begins with other missions.