Ron Athey and Juliana Snapper give their definition of the term “Double Voiced” through reference to their operatic performance which Athey will also call a “genre-stretching theatrical work”: The Judas Cradle.
From Encyclopedia Project, Vol. 1 A-E, ed. Tisa Bryant, Miranda Mellis & Kate Schatz, Encyclomedia, January 1, 2006.
Part I: by Ron Athey.
Part II: by Juliana Snapper.