Question: What is the spiritual significance of the sound of AUM?Sri Chinmoy: The spiritual significance of the sound of AUM is earth's cry for Heaven's smile. This cry of earth ascends to the Highest Absolute. The Highest Absolute descends to the earth-cry, for they need each other. Earth needs the smile of Heaven so that it can claim that it is complete and perfect. And when Heaven hears the cry of earth it feels that it is complete and perfect. It is not that Heaven feels a kind of malicious pleasure from earth's cry, far from it. Only Heaven feels that earth has the real need for something high, divine and sublime. When a child has a real need for milk he cries and the mother immediately gives the child milk. But if the child is not crying for milk and the mother gives him milk, he will just throw it away. This happens quite often. But when earth feels a real need it cries and then Heaven has the opportunity to give what it has: Light infinite.
Sri Chinmoy, The height of silence and the might of sound, Agni Press, 1974