When people hear Anna-Maria Hefele sing, they wonder how she does it, and not just because of her impressive traditional chops. "While most of us struggle to voice one clear, distinct note," writes the Independent's Christopher Hooton, the polyphonic overtone singer Hefele "can sing two at once, and move them around in separate scales." Also known as "throat singing," this technique "allows her to establish a fundamental note and then move the overtone above it through different notes, creating an astounding, ethereal effect." With nothing more than what nature gave her, in other words, Hefele manages to achieve a vocal effect more striking than most anything heard as a result of even today's most complicated digital processes.

But what, exactly, is going on when she sings? These two videos, recorded with Hefele performing inside a magnetic resonance imaging machine at the Institute for Musician's Medicine at the University Medical Center Freiburg, shed light on the mechanics of polyphonic overdone singing. "What you see in this dynamic MRI-recording is the tongue movement in the vocal tract while doing overtone singing and normal singing," says the description.









"The positions of the tongue forms the resonance cavities which delete all not-wanted overtones in the sound of the voice at a certain point in time, and then amplify a single overtone that is left, which can be heard as a separate note above the fundamental." It has, in other words, as much to do with suppressing all the tones you don't want to sing as with emphasizing the ones you do. Hardly the easiest musical trick to pull off, much less inside an environment as unforgivingly noisy as an MRI machine.

But you can still learn the basic techniques, and from Hefele herself at that: previously here on Open Culture we've featured Hefele's own demonstration of and how-to lessons on overtone singing. No matter how well we ourselves learn to sing two notes at once, though, we'd nevertheless have little idea what's going on to let us make such sounds without these revealing MRI videos. (Others have similarly exposed the inner workings of beatboxing and opera singing.) The footage also underscores the respectable musical taste of Hefele herself or her collaborators in this research project, selecting as they have the musical examples of "Sehnsucht nach dem Frühlinge" by Hefele's countryman Wolfgang Amadeus Mozart and "By This River" from singing advocate Brian Eno's classic LP Before and After Science — though you might call this an example of music made during science.

Related Content:

Musician Shows How to Sing Two Notes at Once in Mesmerizing Video

How to Sing Two Notes At Once (aka Polyphonic Overtone Singing): Lessons from Singer Anna-Maria Hefele

Scientific Study Reveals What Made Freddie Mercury’s Voice One of a Kind; Hear It in All of Its A Cappella Splendor

The Hu, a New Breakthrough Band from Mongolia, Plays Heavy Metal with Traditional Folk Instruments and Throat Singing

What Beatboxing and Opera Singing Look Like Inside an MRI Machine

Brian Eno Lists the Benefits of Singing: A Long Life, Increased Intelligence, and a Sound Civilization

Based in Seoul, Colin Marshall writes and broadcasts on cities, language, and culture. His projects include the book The Stateless City: a Walk through 21st-Century Los Angeles and the video series The City in Cinema. Follow him on Twitter at @colinmarshall or Facebook.