In Russian Orthodox liturgy of 16th-18th centuries, polyphony (Russian: многогласие, mnogoglasiye, literally "many-voicing"), sometimes polyvocality, was a tradition to perform several parts of the church service in the same place at the same time, in particular, to sing several different chants simultaneously, to save time. Despite being banned in favor of (monophony (Russian: единогласие, edinoglasiye, literally "single-voicing"), singing the chants one by one consecutively, it persisted for quite some time.
History
The tradition polyphony arose in early 16th century when chants transformed from recitative to elaborate singing. At the same time the strict service regimen adopted in monasteries have become norm in ordinary chcurches. As a result the full church service had gradually become extremely long. Polyphony was introduced at the excuse of saving time and stamina of laymen, however it have gradually evolved to an absurd where, according to complaints, up to 6 chants were sung at the same time, with cantors trying to overshout each other. The Stoglavy Sobor, already in mid-16th century forbade the polyphony, but struggle with it continued for a long time since.