The Venetian polychoral style was a type of music of the late Renaissance and early Baroque eras. It involved spatially separate choirs (cori spezzati) singing in alteration. The style arose from the observed sound delay caused by the distance between the opposing choir lofts in Basilica San Marco, making it difficult for the cori spezzati to sing simultaneously. Composer Adrian Willaert, maestro di cappella of San Marco 1527-1562, solved this problem by writing antiphonal music, where the cori spezzati would sing successive, often contrasting musical lines. The development of this style represented a major stylistic shift from the polyphonic writing of the middle Renaissance to the Baroque era. Source: https://en.wikipedia.org/wiki/Venetian_polychoral_style Image source: http://i44.tinypic.com/2lkdypt.jpg (public domain)