Albert Barnes Commentary 1 Chronicles 15:16

"And David spake to the chief of the Levites to appoint their brethren the singers, with instruments of music, psalteries and harps and cymbals, sounding aloud and lifting up the voice with joy." — 1 Chronicles 15:16 (ASV)

The singers—Singing had long been recognized as appropriate to religious ceremonies (Exodus 15:21; Judges 5:1; 1 Chronicles 13:8), but this is the first occasion on which we find the duty of conducting musical services expressly laid on the Levites. Henceforth, the services of the tabernacle and the temple were regularly choral, and a considerable section of the Levites was trained in musical knowledge and set apart to conduct this portion of the national worship.