In harmonic singing, the singer emphasizes a selected upper harmonic of the vocal pulse. In this way, he can sing two notes at once, the fundamental and the selected harmonic. Members of the Harmonic Choir have developed techniques for the following effects: (1) The fundamental is constant while the selected harmonic varies; (2) the fundamental varies in a melody while the selected harmonic remains constant, leading to parallel harmony; (3) both the fundamental and the selected harmonic vary, either in converging or in diverging directions. The Choir together performs unaccompanied works which are composed but not scored. Different performances follow a common path but differ in many details.