Bhagavad Gita · Arjuna Vishada YogaChapter 1, Shloka 19 (1.19)

Two sounds, two effects. Madhusudana Sarasvati makes this comparison clear: the sound of conches and the rest in the Kaurava army, though extremely tremendous, could not shake the Pandavas; but the blast of conches arising in the Pandava army tore through the hearts of all Dhritarashtra's kin — including Bhishma and Drona. And he explains what "tearing the heart" means: it caused pain (vyatha) like having one's heart torn. That is, this describes an emotional blow, not a literal physical wound.

Why such an effect? The shloka does not give the reason. Some possible readings:

1. The intensity of the sound: according to Madhusudana the sound was "tumula" — intense — echoing through the sky and the earth.
2. Fear within: a side that is not fully confident of its cause from within finds the roar of its opponent heavier. We have already seen Duryodhana's anxiety (1.2–1.11). This is an interpretation.
3. A message for the listener: Sanjaya is telling this to Dhritarashtra — whose sons are losing the war. Sanjaya's account is also a mirror of truth held up to the king.

Poetic exaggeration in the account: "The sky and the earth resounded" — this is poetic style, showing the vastness of the sound. It is right to understand it as poetic description.