Question: How is the inner sound produced?

Sri Chinmoy: It is not actually produced; it spontaneously exists. Everything that can be known or seen in the material world has a source, whereas this soundless sound has no source. Its origin is the Supreme, whom we call Brahman. AUM is a symbol of Brahman. It is the Source itself. If we know that the Ganges comes from the Himalayas, we can climb to the top of the Himalayas and see the source for ourselves. But we will never find a source for the soundless sound. It is like trying to find the origin of the Supreme. It is its own origin. That is why it is difficult for us to understand.