'O-U-M' is the basic sound of the universe!
A long time ago in one of my articles published on SpeakingTree website, I said, 'O-U-M' is actually the basic sound of the universe. The vibration and rotation is going on all over the universe. From there the 'O-M' or 'O-U-M' is always being produced.
Since there is no air in the universe, that sound does not reach our ears. But it is possible to record that sound by suitable mechanical means. Just as a motor makes a hum like 'O-M' or 'O-U-M' when it moves or spins, so does the 'O-U-M' sound from the moving and vibrating universe.