Mantra Vidya, the science of mantra, treats sound not as decoration for prayer but as a technology in its own right. A mantra is a specific sequence of syllables — sometimes a single seed sound, sometimes a full verse — whose repetition (japa) is held to produce a real effect on the mind and, in the tradition’s view, on subtler dimensions of reality, independent of whether the practitioner intellectually understands its meaning.
This rests on the concept of Shabda Brahman, the idea that sound itself is a fundamental layer of reality, prior to and underlying form. OM, often called the pranava or root mantra, is described in the Mandukya Upanishad as containing within its three sounds (A-U-M) the entirety of waking, dreaming, and deep sleep consciousness, plus a fourth silent state, Turiya, beyond all three. Every other mantra is understood as an elaboration of this single primordial vibration.
Mantras are traditionally received from a qualified teacher rather than picked from a book, because correct pronunciation, rhythm, and intention are held to matter as much as the words themselves — the same syllables chanted carelessly and chanted with precision are considered to have different effects. This is why mantra practice sits at the intersection of Sanatan Dharma’s ideas about sound, consciousness, and the guru-disciple relationship all at once.