וְהַמְשֹׁ֣רְרִ֔ים הֵימָ֥ן אָסָ֖ף וְאֵיתָ֑ן בִּמְצִלְתַּ֥יִם נְחֹ֖שֶׁת לְהַשְׁמִֽיעַ׃
So the singers, Heman, Asaph, and Ethan [, were appointed], with cymbals of brass to sound aloud;
Rashi on I Chronicles
And the singers: Heman, Asaph, and Ethan, etc. To make a resounding voice, they were appointed over those musical instruments.