From the book "Jap Ji – The message of Guru Nanak", written by Sant Kirpal Singh

There are many kinds of sounds echoing and re-echoing in the various regions of the creation and may, for convenience, be classified into two categories:

(1) Sound proceeding from the left side. These are negative and material sounds and are connected with the respective ingrained seeds of inner passions. The devotee is willy-nilly attracted by these sounds. If one is fascinated by any one of these siren-songs on the left, one may find oneself hurled down into the deepest depths of the abysmal chasms of the passion to which the particular sound relates, for such sounds have a pull that is outward and downward. In such a sad predicament, the labour of years becomes of no avail and odds go against the pilgrim-soul. These are therefore to he avoided scrupulously, for they lead one astray from the spiritual Path.

(2) Next there are sounds that proceed from the right side. These are sounds from the spiritual planes and as such are positive in character and purely spiritual with a characteristic pull that is inward and upward.

These two kinds of sounds are so very similar and so closely resemble each other that one can hardly distinguish between them. Maulana Rumi, therefore, warns us to be careful in differentiating the right type of sounds. He says:

There are sounds of a lower nature which very much resemble those of the higher,
Yet they have a downward pull and drag on to one's doom.

The particular Sounds that have an upward pull are five in number, as stated by the various Saints, and may be apprehended through their grace and contacted in Their company. Such Sounds carry with them the effect of the spiritual planes from which they proceed and in turn produce the same effect on him who comes in contact with them. They have their own heavenly melodies, the rapturous strains of which depersonalises the soul by freeing it from the chains of mundane life.

Whoever comes near the fire, gets warmth, no matter whether he does so of his own accord or not. So the Holy Naam or the Divine Song, cannot but influence you when you come in contact with It, whether you will it or not and are in time or out of time. The Power of God cannot but influence you, should you get in touch with it.

The outer music has a marvellous effect on all living beings. It shakes off the grievous burden of the oppressive sorrow and unrest under which one incessantly groans and drives away all thoughts. It washes away the dirt of everyday life by its melodious tunes and captivates the soul. It withdraws the mind from the tumultuous hubbub of the objective world. It concentrates the mind, naturally, without having recourse to any fabricated methods. Music, indeed, has ever been the art of saints.

What passion cannot music raise or quell?
Dryden

How marvellous is the effect of the external music! What then will be the charm of the internal Divine Melody? It has its own inimitable fascination. It is exuberant with the spiritual vitality which takes man above all the pains and ills to which the flesh is heir. In times of storm and stress, one may harmonize one's self with the internal tunes and pass off unscathed from the pinching effects of worldly life.

These spiritual sounds are aids on the spiritual Path. A Competent Master, at the time of initiation, gives full instructions on how to differentiate between them from plane to plane, as well as how to catch hold of them on the onward march to the highest spiritual realm.

Herein then lies the need for a Master-soul, for He is the inspirer of Hari Naam – the Divine Word, in the depths of one's soul. Without Him, the Eternal Song ever remains a shrouded mystery with no access thereto. As Music personified, it is within His competence to manifest it, make it audible and thus lead one to the seat of the Almighty.

A Gurmukh (saint) can free millions of souls
by the quickening influence of his life-impulse (the Holy Naam).
Sorath M.5