loud engine reving noise repeated constantly regardless of location, affected by hostile mob volume control

There is a constant, repeating sound that sounds like an engine revving. it will make this sound for a second, stop and repeat. this happens anywhere, in my house, on a tall tower, underground in a mine. it seems to happen more often in some locations, but it's completely random. absolutely no mobs in site. I think it's a small segment of the enderman stare stuck in loop, but it sounds a little deeper pitched. highly annoying, but don't want to turn off hostile mob sounds for fear of ambush. please help