Shabda Brahman
Brahman as the cosmic principle of sound.
Before creation, Brahman manifested as Shabda (sound/word). All manifestation emerges from this primordial vibration. The Vedas are considered eternal sound-forms of reality.
In the beginning was the Word (Shabda), and the Word was with Brahman.
Sound is understood as a fundamental creative principle.
Various Upanishads