Valmiki Ramayana Yuddha Kanda Sarga 81 Shloka 34
Original Shlokaवानराश्शुश्रुवुश्शब्दमदूरेप्रत्यवस्थिताः । व्यादितास्यस्यनदतस्तद्दुर्गंसंश्रितस्यतु ।।6.81.34।।
1 source checked for this shloka
व्यादितास्यस्य waiting for the war, तत् those, दुर्गम् difficult, संश्रितस्य to access, नदतः roaring, शब्दम् sound, अदूरे not far, प्रत्यवस्थिताः to enter, वानराः Vanaras, शुश्रुवुःheard
The sound of his roar was heard by the Vanaras waiting for war standing not far from there, which was difficult for Indrajith to access.