A human being is defined to be an ensemble of the gross (physical) body, subtle (mental and energy) body and astral body (the iner self or the domain of the soul). The existence of three perennial expressions of thy powers of the trinity Gods - Brahma, Vishnu and Shiva, is said to be vital for the manifestation of Nature and life. the existence of the three bodies is similarly an integral part of the existence of any living being in this world. The three bodies, like the triveni - confluence of the holy rivers Ganga, Yamuna and Saraswati are separate as well as one - being the interwoven segments of a single individual self.
Refinement and development of any one of these bodies would be incomplete without the other two. Therefore, when we talk about the role of Sabda or mantra vijnana in human life, we must analyze the respective effects on each of the three forms (bodies) of a human being.
Our world is physically constituted by three basic energies viz. Sound, Light and Heat. According to the electromagnetic wave theory, the ever expanding universe is described as a limitless ocean of energy waves. Grasping and utilization of some of these has given rise to the inventions and discoveries lioke radio, telephone, X-rays, radio-rays, laser, gamma-rays, …….., etc. Enormous combinations of super imposition of compatible waves are supposed to give rise to the energy particles, various subtle particle-states and ultimately to the atomic and molecular forms of matter. The root cause of the existence of different physical forms/states of any kind of material - however subtle or gigantic it might be - is the 'collision or superimposition' of some of these omnipresent, ever vibrating, energy waves.
The eternal forms of sound and vibrations are synonymous with respect to their physical existence. Noting this, a natural conclusion of the above theory would be that - Sabda and nada are the origins and the ultimate controllers of everything that exists (in gross or subtle form) or happens (including the manifestation of life and death) in this universe. Our gross, subtle and astral bodies are thus naturally affected by 'sound'.
Our gross body is a physical system consisting of bio-physicochemical components. The impact of sound on this system results in corresponding vibrations in the molecular, cellular (e.g. an enzyme in a cell or a membrane, or a hormone….) or organ (e.g. the liver, uterus or ears…..) components and generates isolated or cascade effects (positive or negative, depending on the type of sound) on the interconnected subsystems. Several examples of the negative physical effects of the impact of sound on the gross body have been described earlier in the context of the Doppler Effect and noise pollution…… Examples of the positive physical effect (on the gross bodies of any living being), apart from those described earlier include - increase in the immunity of human beings under specific therapies based on sound; acceleration of the growth rate of vegetation by special music….., increase in the reproduction rates of some varieties of fishes and hens under certain music-based treatments…..