Valmiki Ramayana Yuddha Kanda Sarga 53 Shloka 21

तत्र there, द्रुमाणांशिलानांच trees and rocks, शस्त्राणांच weapons also, घोरः fierce, हृदयभेदसः pierced hearts, सुमहान् loud, निःस्वनः in the battlefield, श्रूयते heard.

There, a very loud fearful noise was heard which pierced the hearts in the battlefield, that was produced by the striking of weapons with trees and rocks.