Shabda Brahman is considered in some schools of Hindu thought to create the universe as the “cosmic sound” that is a part of all beings. Many scriptures note that sound and words are eternal: once spoken, they live on as part of the universe as a whole. This concept is fundamental to the use and importance of Om.
Others note that Shabda Brahman is when God manifests as sound and word, and when knowledge is given through scriptures. It is considered the unmeasurable and uncontainable sound of the Vedas. It is expressed through prana as well as through physical senses and the mind.