The potency of transcendental sound vibration lies in its’ being non-different from the Original Cause or Supreme Soul, also referred to in Sanskrit as Bhagavan.
In this world, our experience is that the name of a material object is different from the object itself. The word “mango” is made of syllables which when vibrated or spoken, refer to the fruit – mango. The syllables of this word do not contain the potency to cause an actual mango to appear before me or for me to taste. I can repeatedly chant “mango, mango, mango”, but no mango will be present before me. These are just “empty” words which reflect a separate reality.
Transcendental sound vibration is not like this. It is full of spiritual potency and non-different from the Original Cause, or Supreme Soul. Therefore, by chanting these transcendental sound vibrations one is directly associating with, and being purified by, the Original Cause or Supreme Soul.
One may ask how this transcendental sound descends to the material world for me to use?
The answer is that the sound is received from a spiritual teacher, who is the transparent medium of the mantra or the transcendental sound. This transcendental sound descends from the spiritual dimension and is transmitted through an unbroken succession of spiritual teaches, through what is called guru-parampara or sometimes referred to as disciplic succession.
In order to experience the full potency and benefit of a mantra or transcendental sound, one must receive in such a way.
सम्प्रदायविहीना ये मन्त्रस् ते निष्फला मताः
mantrās te niṣphalā matāḥ
If one is not actually connected with a bona fide disciplic succession, whatever mantras he chants will not bring the desired result. – Padma Purāṇa