The sound reached the hearts of those who heard it.

The conch shells of the Pandava army were so large, deep, and terrifying that their sound filled heaven and earth. And this sound not only echoed across the battlefield but is described as having "torn" the hearts of Dhritarashtra's sons.

Until a while ago, the Kaurava army was also making loud noises. However, here, the sounds from the Pandava side create fear and pressure within the enemy. The conch shells are depicted not only as signals for the start of battle but also as conveying the fighting spirit and conviction of those who fight, and having the power to shake even the hearts of the enemies.

Japanese Translation from the Geeta Press Edition - Chapter 1, Section 19: "That Sound Tore My Heart."

That sound pierced the hearts of all the beings. The sky and the earth were filled with a rumbling noise. || 19 ||

Translation

That terrible sound, Resounded throughout heaven and earth, And tore apart the hearts of the sons of Dritarashtra.

Annotative Translation

When all the trumpets of the heroes in the Pandava army were blown simultaneously, the sound that arose was extremely loud, high-pitched, deep, and terrifying.

That sound filled all regions of heaven and earth.

Those sounds spread widely across those areas, creating resonance, and echoing throughout the entire land and sky.

And that caused great fear and terror among the sons of Dritarashtra, and other warriors who were on their side.

They felt a sudden pressure in their hearts, as if they had been torn apart.