ייִדישער מחשבֿה אויף ויקרא 4:26

The Levites did not sacrifice; they were not considered as being agents in the atonement of sins, for it was only the priest who was commanded “to make atonement for him” (Lev. 4:26) and “to make atonement for her” (Lev. 12:8). The duty of the Levites was the performance of vocal music; and a Levite became therefore disabled for service when he lost his voice. The object of the singing is to produce certain emotions; this object can only be attained by pleasing sounds and melodies accompanied by music, as was always the case in the Temple.