"Overtone singing is a voice technique where one person sings two notes at the same time," explains Hefele in the video above. On her website, Hefele says this style is originally from Mongolia, locally known as Sygyt.
Watch Hefele show off her perfect control, as she is able to sustain one constant low note, while simultaneously singing a high-pitched scale. It seems impossible that the sounds are coming from just one woman, and Hefele's vocal control might leave you wondering if she is even human.
But she is not new to the craft. Hefele has been studying throat singing since 2005, and is a classically trained singer who plays instruments like the harp, mandolin, piano, didgeridoo and Schwegel.