Before a single word of the teaching, the Gītā is loud.
At 1.12 the grandsire Bhīṣma roars and blows his conch. At 1.13 conches, drums and horns sound together. Then, at 1.15 and 1.16, each hero on the other side blows his own, and every conch has a name: Kṛṣṇa’s Pāñcajanya, Arjuna’s Devadatta, Bhīma’s Pauṇḍra, Yudhiṣṭhira’s Anantavijaya, and Sughoṣa and Maṇipuṣpaka for the twins.
Six named shankhs. The same sound still opens every aarti.
The verses
BHAGAVAD GĪTĀ · 1.12तस्य संजनयन्हर्षं कुरुवृद्धः पितामहः।
सिंहनादं विनद्योच्चैः शङ्खं दध्मौ प्रतापवान्।।
tasya sañjanayan harṣaṁ kuru-vṛddhaḥ pitāmahaḥ
siṁha-nādaṁ vinadyoccaiḥ śaṅkhaṁ dadhmau pratāpavān
Then the valiant grandsire Bhisma, the senior-most of the Kuru clan, roared like a lion and blew his conch with the intention of cheering up Duryodhana.
BHAGAVAD GĪTĀ · 1.15पाञ्चजन्यं हृषीकेशो देवदत्तं धनंजयः।
पौण्ड्रं दध्मौ महाशङ्खं भीमकर्मा वृकोदरः।।
pāñcajanyaṁ hṛṣīkeśo devadattaṁ dhanañjayaḥ
pauṇḍraṁ dadhmau mahā-śaṅkhaṁ bhīma-karmā vṛkodaraḥ
Sri Krishna blew his conch, Pancajanya, Arjuna his Devadatta, and Bhima of terrible deeds blew his great conch, Paundra.
BHAGAVAD GĪTĀ · 1.16अनन्तविजयं राजा कुन्तीपुत्रो युधिष्ठिरः।
नकुलः सहदेवश्च सुघोषमणिपुष्पकौ।।
anantavijayaṁ rājā kuntī-putro yudhiṣṭhiraḥ
nakulaḥ sahadevaśca sughoṣa-maṇipuṣpakau
King Yudhisthira, the son of Kunti, blew his conch, Anantavijaya, and Nakula and Sahadeva blew their conchs, Sughosa and Manipuspaka.
Going deeper
Before any teaching, chapter 1 gives the sound of the two armies. 1.12 has Bhīṣma, eldest of the Kuru clan, roar like a lion and blow his conch to cheer Duryodhana. 1.13 follows at once: conches, kettledrums, trumpets and horns all sound together, and the noise is terrific. In 1.14 Kṛṣṇa and Arjuna answer from their chariot with white horses. 1.15 names the conches of Kṛṣṇa, Arjuna and Bhīma, and 1.16 names those of Yudhiṣṭhira and the twins. 1.17 and 1.18 go on to the other warriors, each blowing a conch. Only after all this noise does Arjuna ask Kṛṣṇa to draw the chariot between the armies, which the next verses describe. The conch is how the Gītā begins to speak: loudly, with names, before a word of teaching has been said. See chapter 1 and what the Gītā says about courage.