Text 12

tasya sanjanayan harsam
kuru-vrddhah pitamahah
simha-nadam vinadyoccaih
sankham dadhmau pratapavan

Translation

Then Bhishma, the great valiant grandsire of the Kuru dynasty, the grandfather of the fighters, blew his conchshell very loudly, making a sound like the roar of a lion, giving Duryodhana joy. 

Commentary by Srila Prabhupada 

The grandsire of the Kuru dynasty could understand the inner meaning of the heart of his grandson Duryodhana, and out of his natural compassion for him he tried to cheer him by blowing his conchshell very loudly, befitting his position as a lion. Indirectly, by the symbolism of the conchshell, he informed his depressed grandson Duryodhana that he had no chance of victory in the battle, because the Supreme Lord Krishna was on the other side. But still, it was his duty to conduct the fight, and no pains would be spared in that connection.

Commentary by Sri Vishwanatha Chakravarthi Thakur

Bhisma, the elder of the Kurus, joyful on hearing respect given to him, and to produce joy in Duryodhana by driving away his fears, roaring like lion, blew his conch shell. The phrase simha-nadam vinadya uses the same root nod twice. The literal meaning is roaring the roar of a lion. The intended meaning is "roaring like a lion," according to the sutra upamane karmani. (Panini 3.4.45)