Abstract
Khoomei is a unique singing style originating from the republic of Tuva in central Asia. Singers produce two pitches simultaneously: a booming low-frequency rumble alongside a hovering high-pitched whistle-like tone. The biomechanics of this biphonation are not well-understood. Here, we use sound analysis, dynamic magnetic resonance imaging, and vocal tract modeling to demonstrate how biphonation is achieved by modulating vocal tract morphology. Tuvan singers show remarkable control in shaping their vocal tract to narrowly focus the harmonics (or overtones) emanating from their vocal cords. The biphonic sound is a combination of the fundamental pitch and a focused filter state, which is at the higher pitch (1-2 kHz) and formed by merging two formants, thereby greatly enhancing sound-production in a very narrow frequency range. Most importantly, we demonstrate that this biphonation is a phenomenon arising from linear filtering rather than from a nonlinear source.
Highlights
In the years preceding his death, Richard Feynman had been attempting to visit the small Asian republic of Tuva (Leighton, 2000)
Most of the energy in their song is concentrated in the overtones and no subharmonics are observed
In contrast to these three singers, singer T4 performing in a non-Sygyt style exhibited a fundamental frequency of approximately 130 Hz, signi cant energy appears around 50-55 Hz, well below an expected subharmonic (Fig.5)
Summary
In the years preceding his death, Richard Feynman had been attempting to visit the small Asian republic of Tuva (Leighton, 2000). A key catalyst came from Kip Thorne, who had gifted him a record called Melody tuvy, featuring a Tuvan singing in a style known as “Khoomei", or Xöömij. He was never successful in visiting Tuva, Feynman was captivated by Khoomei, which can be best described as a high-pitched tone, similar to a whistle carrying a melody, hovering above a constant booming low-frequency rumble. Such is a form of biphonation, or in Feynman’s own words, “a man with two voices". Does one singer produce two pitches at one time? Even today, the biophysical underpinnings of this biphonic human vocal style are not fully understood
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