The Levites stood up, by Jehoshaphat's appointment. With a loud voice on high, i.e. with most loud voice, with heart and voice lifted up; whereby they showed their full assurance of the victory, as if it were already accomplished.
Related Commentaries of 2 Chronicles 20:19
2 Chronicles 20:19
19 And the Levites, of the children of the Kohathites, and of the children of the Korhites, stood up to praise the LORD God of Israel with a loud voice on high.