The Yogi knows that the first thing you hear in the Anahata, when the mind becomes calm, quietly enjoying, contemplating on the inner Shivam, is dum, dum, dum, the damru. Normally you don’t hear because you are so engrossed in the gross sounds of the outside. Deep inside it is dum, dum, dum, the damru. Which means it’s a signal that the Yogi is moving towards the light, the Jyoti.