One Singer, Two Voices

Introduction: Rendering Melodies with Overtones A single singer but two voices? Experience that situation by visiting world-voice-day.org/EDU/Movies and check the second movie with the title “Sehnsucht nach dem Frühlinge (Mozart) — Anna-Maria Hefele (AMH). There, coauthor AMH sings a song by Mozart, first with her singing voice and then with two simultaneous voices, a drone (a low-pitched, continuously sounding tone) plus a whistle-like high-pitched tone that renders the melody. How is this possible? That is the question that we pose here. Let us start by recalling how sounds are created by the instrument AMH is playing, the human voice.