What do the Mach 12+ scramjet engine and the human voice have in common? For starters, both are able to use sound waves in an incredibly efficient manner.

Let's take a look at how one human voice can be heard over a full orchestra, (and how one screaming baby can ruin the concert).

Okay. I'm a little geeky, but one day, as I was looking at the engine of the scramjet, it occurred to me that it is similar to the vocal resonance tract of a trained opera singer.

If you look closely at the "inverted megaphone" shape of a trained singer, where there is an air intake region, a compression chamber and an exhaust vestibule, it is remarkably similar to the engine of the scramjet.

The same principles of lift and drag that allow a jet to stay airborne are in play in the human voice. Just above the vocal folds are the Ventricles of Morgagni, small symmetrical pouches that are vestiges of our simian ancestry. These pouches fill with air and help create the tiny tornadoes (vortices) of air that are present in great singing. The lift of the oscillations helps create the mucosal crest, adding to the harmonic timbre of a well-trained voice.

In the scramjet, the air travels through the jet so efficiently that a minute portion of fuel is compressed to optimize speed. As with the opera voice, drag and turbulence are considerations. One could liken the idea of a horrible, shaky vibrato to a jet reentering the atmosphere at Mach 25. The results could be catastrophic in one case, and highly unpleasant in the other. I'll leave the choice to the reader, as there are some who may prefer experimental jet travel to having to sit through an opera.

Therein lies the problem with our cultures' perception of opera singing. In my well-researched opinion, true vibrato, the kind of which Walt Whitman must have experienced when he writes about the opera piercing his soul and making him weep, may be found when the tiny vortices of air are spinning in a musical (symmetrical) manner; when the sound waves in all six formant tubes are in such exquisite phase that the sound emanates from the singer's soul, through well-trained vocal tracts, to the listener's heart.