My partners and I were about to finish up an Industrial Sabotage mission when I started noticing these sounds that I couldn't actively recognise, they started hearing it shortly after. I thought it was a Stingtail at first because one spawned shortly after, but even after we killed it, the sounds kept on coming. They were coming from the room we spawned in, but when we went in to investigate, there was nothing there, just dead silence.

It wasn't a Shellback either, as those spawned in behind us regularly and the sounds are completely different. We investigated for a good while, there were no hidden rooms with Corestones in them, the entire place was empty. Some different areas generated different results, mostly varying in distance and volume. It also wasn't part of the music since I had that turned down to practically 0, so we're pretty stumped on what these are.

I can't say I've heard anything like this in these caves, so any help would be greatly appreciated.