John Gill Commentary 2 Chronicles 20:19

"And the Levites, of the children of the Kohathites and of the children of the Korahites, stood up to praise Jehovah, the God of Israel, with an exceeding loud voice." — 2 Chronicles 20:19 (ASV)

And the Levites, of the children of the Kohathites, and of the
children of the Korhites
Who were of the posterity of Kohath, in the line of Korah: stood up to praise the Lord God of Israel with a loud voice on high ;
in high notes; they being the course in turn at this time for this service.