Overtone singing is a vocal technique in which a single singer produces a sustained low tone and, at the same time, a separate whistle-like melody made of that tone’s upper harmonics. It is often called throat singing, although research on Tuvan singers points to the whole vocal tract, not the throat alone, as the source of the effect, and the traditions behind it are distinct: Tuvan khoomei, Mongolian khöömei, and a Western experimental lineage that runs from Karlheinz Stockhausen to the Harmonic Choir. For drone music the technique has a particular appeal, because the voice carries its own fixed drone and a moving melody together, with no second performer and no instrument.
One voice, two pitches
In the study “Overtone focusing in biphonic Tuvan throat singing,” published in eLife in 2020, Christopher Bergevin and colleagues describe biphonation as the production of two distinct pitches at once: a low, booming drone with a high, flute-like tone hovering above it. The paper analyzed recordings of four Tuvan singers, three of them performing the sygyt style, and used dynamic MRI on one singer.
The findings run against a common assumption that the two pitches come from two vibrating sources. According to the authors, the drone comes from the ordinary vibration of the vocal folds, while the high tone comes from the vocal tract acting as a filter. By shaping the tongue and mouth, the singer merges two resonances of the tract into one sharp peak, which amplifies a single overtone and suppresses its neighbors. In the sygyt singers this focused band sat roughly between 1 and 2 kHz. The paper also found two constrictions: one near the ridge behind the upper teeth that drives the merging of resonances, and a second in the upper throat, near the uvula, that sets which overtone is selected, which is how the melody is played. Because the vocal-fold source stays steady, the drone does not waver while the melody moves, which is a defining property of the technique.
Tuvan styles
Tuva is the tradition most associated with the technique. A summary of its styles distinguishes several. Khoomei is the most popular and the softest, with a drone in the low-mid to midrange of the voice and two or three audible harmonics one or two octaves above it. Sygyt, named for whistling, pairs a midrange drone with piercing, flute-like harmonics. Kargyraa is a deep, growling style that engages both the vocal folds and the folds above them, and it has two substyles, the deeper dag (mountain) and the raspier xovu (steppe). Borbangnadyr imitates the trill of birds and flowing water, and ezengileer pulses to evoke the rhythm of horseback riding.
The same source states that the technique is practiced in Tuva, Mongolia, Inner Mongolia and the Altay, and that singers often seek out rivers or mountain steppes, where the open landscape lets sound travel far. That link between voice and place connects the practice to the questions raised in the glossary entry on acoustic ecology. Huun-Huur-Tu, a group formed in 1992 that built its repertoire around throat singing, has toured internationally since soon after its founding, according to the same source. The physicist Richard Feynman became interested in the tradition and tried to reach Tuva in the 1980s without succeeding, an effort recounted in the 1988 documentary The Quest for Tannu Tuva.
Mongolian khöömei
Mongolia has its own tradition, with its own name. UNESCO describes Khöömei as a singing art from the Altai mountains of western Mongolia in which performers imitate natural sounds, producing a sustained low tone and a melody of harmonics simultaneously. The word means “pharynx,” and UNESCO notes the belief that the art was learned from birds. Two broad styles are given: kharkhiraa, or deep khöömei, in which the singer sings the drone in a normal voice while emphasizing the subharmonic an octave below, and isgeree, or whistled khöömei, which emphasizes overtones above the fundamental. In both cases the vocal cords stay taut for the drone while the melody is made by changing the mouth cavity and moving the lips and tongue.
UNESCO inscribed the practice on the Representative List of the Intangible Cultural Heritage of Humanity in 2010. Its description is a reminder that the music is not a stage curiosity. Nomads perform it on occasions that range from state ceremonies to household gatherings, while herding, and in the yurt to lull babies to sleep, and it is passed on orally or through master-to-apprentice training.
Stimmung and the Western turn
Western composers came to overtone singing late and from a different direction. Karlheinz Stockhausen composed Stimmung in 1968 on a commission from the city of Cologne, and the Collegium Vocale Köln gave the first performances. The Wikipedia entry on the work lists six vocalists with six microphones, an average duration of about 74 minutes, and a structure built on the harmonics of a low B-flat that the singers tune to but that the audience does not hear. The singers build upward from harmonics 2, 3, 4, 5, 7 and 9, and the score specifies 108 pitches written in just intonation. The same article calls it the first major Western composition based entirely on vocal harmonics. Recordings include the Collegium Vocale Köln for Deutsche Grammophon (1969), Singcircle (1983, Hyperion) and Theatre of Voices (2006, Harmonia Mundi).
Stimmung matters for drone listeners because it treats a single fixed harmonic series as the entire world of the piece. The tuning principles behind it, pure ratios drawn from the harmonic series, are explained in the article on just intonation, and La Monte Young’s The Well-Tuned Piano rests on the same family of ideas, built there from overtone and undertone numbers 2, 3, 4, 6 and 7 on a retuned piano.
David Hykes and the Harmonic Choir
In the United States the best-known figure is the composer and singer David Hykes, who founded the Harmonic Choir in 1975. According to his Wikipedia biography, Hykes studied experimental filmmaking with Tony Conrad, North Indian raga singing with Sheila Dhar, and researched Mongolian, Tibetan and Middle Eastern singing. He also helped bring the Gyuto and Gyume monks to the United States in 1985 and 1986. His piece “Rainbow Voice” appears in films including Baraka (1992), Dead Poets Society (1989) and Blade (1998).
Hykes thus drew on several Asian vocal traditions rather than on a single one, which separates the Harmonic Choir from the Tuvan and Mongolian practices described above, where the technique belongs to specific regions and communities.
Why the voice suits drone music
Listening to the styles side by side makes the differences concrete. In khoomei, the drone dominates and a couple of soft harmonics float one or two octaves above it. In sygyt, the upper line becomes a clear whistle that can be followed as a melody. In kargyraa, the emphasis falls on a deep, rough lower register, and the Mongolian counterpart, kharkhiraa, stresses the subharmonic an octave below the sung tone. A recording of each, played in a quiet room, shows how much variety fits inside the idea of a voice that holds one pitch.
Across the traditions above, the structure is consistent: a fixed low tone carries a melody made from its own overtones, with no electronics and no second performer. That interior melody within a steady tone is what the voice shares, in principle, with the in-tune organ music of Ellen Arkbro and with the sustained works of La Monte Young.
Other traditions of sustained tones are covered in the article on drone in folk music, and the tanpura drone of Indian classical music is the subject of a separate article. For those hearing the technique for the first time, the guide to how to listen to drone music outlines a patient approach: a quiet room, a moderate volume and a single long recording, with attention to the high line above the low tone.
