Shabda Brahman
Shabda Brahman or Sabda-Brahman or Nada Brahman means transcendental sound or sound vibration or the transcendental sound of the Vedas or of Vedic scriptures.
Shabda or sabda stands for word manifested by sound and such a word has innate power to convey a particular sense or meaning.
In Hindu philosophy
According to the Nyaya and the Vaisheshika schools, Shabda means verbal testimony; to the Sanskrit grammarians, Yaska, Panini and Katyayana it meant a unit of language or speech or vac. In the philosophical terms this word appears for the first time in the Maitri Upanishad that speaks of two kinds of Brahman - Shabda Brahman and Ashabda Brahman. Bhartrhari speaks about the creative power of shabda, the manifold universe is a creation of Shabda Brahman. Speech is equated with Brahman.The Rig Veda states that Brahman extends as far as Vāc, and has hymns in praise of Speech as the Creator and as the final abode of Brahman. Time is the creative power of Shabda Brahman.Purva Mimamsa deals with Shabda Brahman which is endowed with names and forms and is projected in vedic revelations. Vedanta deals with Parama Brahman which is transcendent and devoid of material names and material forms. One has to become well established in Shabda Brahman before realizing Parama Brahman. Vedas are not the product of conventional language but the emanation of reality in form of Shabda which is the sole cause of creation and is eternal. Purva Mimamsa, an esoteric discipline, from the point of view of spiritual growth aims at attaining the heavenly happiness by realizing Shabda Brahman by conducting yajnas that help control the senses and the mind; when the mind and the senses are subdued the inner subtle sound is realized as Shabda Brahman.
In Indian classical arts
The fundamental theory of Indian classical music, art and poetry is grounded in the theory of Nada Brahman or Shabda Brahman, and is linked with the Vedic religion. The Apara Brahman mentioned by Mandukya Upanishad is Nada Brahman or Shabda Brahman. Shiva Samhita states that whenever and wherever there is causal stress or Divine action, there is vibration, and wherever there is vibration or movement there sound is inevitable. "M" of Aum, the primordial vac represents shabda which is the root and essence of everything; it is Pranava and Pranava is Vedas, Vedas are Shabda Brahman. Consciousness in all beings is Shabda Brahman.When the necessity of directing the Mantra internally and to objects externally is transcended then one gains Mantra chaitanya which then awakens Atman chaitanya, the Divine Consciousness, and unites with it. The Mantra is Shabda Brahman and Ishta is the light of Consciousness. The prana, body and mind along with the entire universe, are all expressions of Mantra chaitanya. At the ultimate level of Shabda Brahman transcendental words become materially wordless, transcendental forms become materially formless and all multiplicity unified in Consciousness residing in that transcendent glory extends beyond mind and speech.