Silence everything around you. The TV, your computer, the fans, EVERYTHING except the lights. If everything else is completely quiet, you may notice that there is a slight ringing in your ears. Don't worry about that sound. Now do the same thing again; Silence EVERYTHING. But THIS time turn off all the lights and make sure there's pitch darkness. If you did it correctly, you may notice no more ringing. But you better pray to god that you do hear it, or that you're just mishearing it, because if you truly don't hear it anymore, that means they've broken through. And no amount of running will ever save you.