Whenever I am driving above like 10-15mph, I notice this kind of intermittent-sounding noise coming from under the hood. The best I can describe the noise is what you get from wind on the freeway except it sounds intermittent. It almost sounds like maybe something is spinning kind of dry and makes this sound?

Anyone know what's causing this?

Edit: Good way to describe the sound - Imagine someone shuffling a deck of cards really fast.