Even the organ had as yet acquired no independent office, but simply supported voices by doubling their notes.

It seems unlikely, then, that the pipe in "Orfeo" could have had a real part.

What it probably did was to repeat as a sort of ritornello the clearly marked refrain of the song.

This would have been thoroughly in keeping with the growing tendency of the frottola to use refrains and advance toward strophical form.
The lyre, with which Baccio Ugolino as Orfeo accompanied himself, may have been a cithara, but the probabilities are that it was not.

As late as the time of Praetorius's great work (Syntagma Musicum) the word "lyra" was used to designate certain instruments of close relationship to the viol family.