 In part, it was based on the extant sixteenth-century practice of performing polyphonic madrigals with one voice singing the treble line, while the others were played by instruments or by a single keyboard instrument.Thus, while all voices were still theoretically equal in these polyphonic compositions, in practice the listener would have heard one voice as being a melody and the others as accompaniment.Furthermore, the new musical genres that appeared in the late sixteenth and early seventeenth centuries, especially the instrumental sonata, revealed a transition in ways of thinking about composition and performance, from a collaboration of equals to a soloist backed up by a relatively unimportant accompaniment.