Anna-Maria Hefele is apparently a master of polyphonic overtone singing.

Also known as throat singing, there are several styles of throat singing. Mastery of such a skill allows a person to sing two notes at one.

It can seem a bit unsettling at first, but I assure you it’s worth the watch. Particularly at 3:25 where she’s able to move both notes in opposite directions. 

Simply astounding. Check it out.