The concept sits in the Vedas and Upanishads: nada, sound or vibration, plus brahman, the impersonal cosmic principle, not the creator deity. The Nada Bindu Upanishad instructs listening inward as gross vibration refines into subtler tones; the Mandukya Upanishad, twelve verses total, maps AUM onto consciousness: A is waking, U is dream, M is deep sleep, and the silence after is turiya, the fourth. The tradition splits sound into ahata, struck, audible, and anahata, unstruck, the inner sound of deep meditation. Pythagoras's music of the spheres, per his third-century biographer Porphyry, is the Greek parallel, audible to him alone.
The phrase reached the West through Joachim-Ernst Berendt's 1983 book and became the charter of sound healing: singing bowls, gongs, frequency lists, the 432 versus 440 Hz dispute. A 2011 pilot fMRI study found OM chanting associated with limbic deactivation, possibly via vagus stimulation, a real but tiny preliminary result, n of 12, constantly cited as proof of the whole system. The wellness syllogism: everything vibrates, words are vibrations, therefore words restructure reality, the same engine as the Emoto file, now with bowls.
The claim: anahata is epistemically elegant to the point of suspicion, a cosmic sound audible only to advanced practitioners, so its evidence is self-certifying and its absence is your deficiency; yet the tradition is honest about the ladder: start with struck sound you can actually hear, and follow it inward. Verdict: the practice instructions are admirably falsifiable, the metaphysics is not, and the archive files the pair separately: the listening is real, the soundtrack of the universe is a claim that only the listener can grade. Porphyry said Pythagoras alone heard the spheres. Every tradition's deepest sound has exactly one earwitness.
If the universe is sound, what instrument is being played, and can it hear itself?