Mongolian Throat Singing Has Two Voices at Once

A throat singer in Tuva or western Mongolia produces two pitches at the same time: a fundamental drone around 60–200 Hz, and a whistling overtone between 1,000 and 3,000 Hz. Acoustically, the drone is always present in any sustained vowel — it's the rest of the harmonic series. What the singer does is sharpen their vocal tract into a very narrow filter that amplifies one specific overtone so much it sounds like a separate note.

How they do it is mechanical. The ventricular folds — a second pair of tissue above the true vocal cords — are tensed to add a buzz, and the tongue, lips, and soft palate are positioned to create a tiny cavity with a single sharp resonance. By moving the tongue back and forth, the singer shifts which harmonic is amplified, producing a melody that rides on top of the unchanging drone.

MRI studies at the University of Washington, led by Sheng Fu and Theodore Levin, have filmed the vocal tract during sygyt (a high-whistle style) and showed the tongue making contact with the hard palate to split the mouth into two resonant chambers. Two chambers, two filters, two audible pitches from one source.

The Tuvan tradition distinguishes at least five styles — khöömei, sygyt, kargyraa, borbangnadyr, ezengileer — each with characteristic drones and ornaments. Kargyraa uses subharmonic phonation that drops the voice an octave below the fundamental, often described as sounding like a very calm bear. UNESCO inscribed Mongolian khöömei on its Intangible Heritage list in 2010. A voice instrument with built-in dual-channel.