Christopher Vila is the inventor and manufacturer of this ravishing music instrument, that leads you in a deep self-forgetfulness when you play it, what you can still feel as a listener: Cosmicbow.
In the video, he demonstrates an incredible control of the first and second formant, by playing two independent melodies simultaneously with both resonances. He controls the deeper overtone with the anterior mouth, the high harmonics are determined mainly by the position of the epiglottis and the root of the tongue.
This skill is an example of how much music is yet to be discovered in our vocal resonance cavities alone. A reference to the vocal Phonetics is interesting, in which also a control of the formants is required to enable the brilliance and load-bearing capacity of the voice, which is required for classical singing. I can recommend any classical singer to play around with the Cosmicbow for a while.