It is a known fact that everything that can exist in the universe as a material form has a vibration associated with it. In ancient Vedic times, this vibration which is intrinsic to the body was called nāda.
In physics, sound is a vibration that typically propagates as an audible wave of pressure which requires a transmission medium. So, even in modern science, sound is considered as a form of vibrational energy which has longitudinal or compression wave pattern when it travels thru gaseous or liquid medium and a transverse wave pattern when it travels thru solid medium.
It is also a known scientific fact that as we lower the temperature of any material, the various motions of the molecule will be reduced, but we are not able to stop the vibrational motion of these molecules even at extremely low temperatures. i.e. Vibrational Energy is fundamental to existence of matter.
Since nāda is fundamental to the existence of any form, it is considered as the very essence of that form. By tapping into this vibrational energy, the nāda of any form we can establish a direct contact with that form, which is not marred by external appearances which are typically based on linguistic and cultural biases.
This forms the basis of Nāda Yoga indicated in Sanskrit as नादयोग, which is an ancient Vedic science of using Sound and associated breath to achieve a state of unison (yoga) within one’s own self as well as unison (yoga) with the Divine.