American Standard Version (ASV):
And these are the singers, heads of fathers’ [houses] of the Levites, [who dwelt] in the chambers [and were] free [from other service] ; for they were employed in their work day and night.
King James Version (KJV):
And these [are] the singers, chief of the fathers of the Levites, [who remaining] in the chambers [were] free: for they were employed in [that] work day and night.