In Indian classical philosophy, it is believed that essentially every thought or idea originates in Sound (nada). The moment we think, an unheard sound is formed. As an idea appears in one's mind, the sound that concurrently occurs is the ground for all forms.

Sound is classified into four stages : Para, Pasyanti , Madhyama and Vaikhari. In an evolutionary sequence, these display the structure of the continuum of manifestation. Para sound, at the unmanifest stage, is the starting point. When the Para sound is elongated in different directions, it becomes Pasyanti. In other words, Pasyanti sound is sound emerging towards the visible. After the stage of Pasyanti, sound begins to crystallise into form. At this stage, sound becomes light or Pasyanti becomes Madhyama , the luminous sound. By creating patterns and curves, luminous sound make the enclosure and definition of space possible, projecting the original sound in forms accessible to human experience. The final stage of Vaikhari sound offers infinite opportunities of permutation and combination arising out of one harmonious primal sound.

In Tantric thought, sound without vibrations does exist. And this unstruck sound or Anahata Dhwani comes from the original Pranava sound, which as the aggregate of all existing sounds gives birth to the cosmic process itself. Through its immeasurably powerful range and intensity, the Anahata Dhwani can create, destroy, and reshape the entire structure of the Universe.