My iPod is making transformer noises!!?

Okay, so recently my iPod has started making random noises that sound like a transformer transforming!! I have no clue why or how, and I have closed all my apps that would possibly be running, and it doesn't seem to help. It happens at random times and I can't figure out what exactly makes it happen. If you are experiencing this or know why/what causes this, help is greatly appreciated. Its really creepy...