It's interpreted either as "shield-song," derived from Old Norse bardi = shield, or as "beard-way" (the humming in the beard), imitating the thunderous voice of the god Donar.
[8] The Barritus opens the battle and is meant to boost the morale of one's own side while intimidating and frightening the opponent.
Depending on the strength of the Barritus, it either startles and frightens the opponent while igniting one's own courage or reveals weakness and a lack of self-assurance.
[4] According to descriptions by Ammianus Marcellinus and Flavius Vegetius Renatus, it seems that in the 4th century, Barritus transformed from a battle cry into a rather simple war chant within the Roman Army.
In the late Roman Army, the Germanic auxiliary troop (Auxilia palatina) known as the Cornuti was famous for their Barritus.