Some of the Levites were musicians in the Temple. The leaders of these families stayed in the rooms of the Temple. Since they were on duty day and night, they did not do other work in the Temple.
So it was in the days of Zerubbabel and Nehemiah. All the people of Israel gave something to the singers and gatekeepers, and they also set aside part for the Levites. Then the Levites set aside part for the descendants of Aaron.