How is Shabd realised?

Through the Grace of the Lord. He alone realizes the Sound on whom the Lord showers His Grace. The Shabd then manifests within him.

When He showers His Grace, the Shabd abides in the heart, and one is rid of all doubts. Body, mind and speech become pure. And the Name dwells in the mind.

Ramkali M1, 944-13

He alone realizes Him  whom the Lord unites with Himself. One is then attuned to the true One Singing day and night the Guru´s Word.

Malar M3, 1259-8

For the one to whom the Lord is kind, the Shabd is coined in the mint of Truth, and he alone meditates upon it.

The Shabd is coined in the mint of Truth. Those on whom He showers His Grace receive it. 

Jap Ji, 8-9

Through Satsang and the Satguru:

When the Lord is kind, we meet a Master who connects our soul with the Sound.

By the Lord's Grace is the True Guru met. And then alone He joins our soul with the Word.

Majh M3, I10-I

This boon can be had only through the Satguru and His Satsang.

He is One and the Shabd is His insignia. He can be realized through a perfect Master.

Basant M1, 1188-15

The perfect Master enables us to hear the Shabd. The three attributes are overcome,  and one attains the fourth state.

Gauri M3, 231-7

The beneficent Master makes us hear Shabd, which stills the wanderlust of the mind.

Gauri M3, 232-6

The Master is Himself the Shabd or the Word made flesh. He alone can manifest the Shabd. The Shabd is a boon from the Master. The Master makes It dwell in our hearts. It is impossible for anyone else to manifest It.

The Shabd of the Guru can be bestowed only by Him. It cannot be manifested by anyone else.

Sarang Var M4, 1249-8

The Sound of Shabd is an unspoken language which is constantly emanating from the mouth of the Lord without being uttered. The Master also gives this Shabd to his disciples in the like manner, without using the tongue.

Maulana Rumi says:

The Master behaves in the same manner as God. He teaches the disciples without speaking.

The Master points to this indescribable and formless Shabd and makes the disciple turn inward. With his power, he then connects the disciple with Shabd.

The Shabd can be had by giving up pride of knowledge, caste and creed, and by sitting at the feet of the Master:

In order to gain this wealth we have to give up pride of knowledge, and to take shelter at the feet of a Master.

Give up pretence to knowledge and devoutness; drink the wine from the divine cup.

Do not let the feelings of 'I-ness', wealth, knowledge, caste, creed or nobility of family or glory come near you. All these lead to stopping of the Sound. Put on the adornment of humility and listen to the Sound, and obtain bliss from its intoxicating powers and sweetness.

If seed is sown in a field which is not prepared, or if it is sown out of season, it does not bear fruit. Similarly, so long as the mind is not rid of its cravings and has not become pure, it does not cease its wandering or running about. The mind becomes pure only through devotion to the Shabd. 

So long as the mind is divided, there is no success. We neither realize the Shabd, nor see the Lord. 

So long as the mind is wandering and there is pride and egotism, the Shabd is not heard and there is no love for Naam. 

Therefore, it is far more necessary to rid the mind of inner uncleanliness than to remove outer impurities.