Can You Mix Whistle and Head? (Your Second Mixed Voice)

There seems to be a lot of confusion on the internet as to whether or not it's possible to blend whistle and head tones. I believe many singers (mostly male) are singing whistle tones when they believe to be singing head tones. It's hard for me to believe that so many teachers have a difficult time understanding that head and whistle are capable of being "mixed."

"...we observed clear bifurcations from "light" to lyrical mode, with discontinuous changes in f0, larynx vertical position, amplitude and shape of the electroglottographic signal. No such discontinuities occurred from C5 to D7 within the "light" mode"

This indicates that from between C5 to D7 in this voice that the soprano ~COULD~ be in whistle OR a head tone which resembles whistle. It wasn't possible for the researchers to identify a definitive break. The soprano is either in M3 at C5 or blending their M2 so well the difference is indistinguishable. 

"All these observations suggest that, for this singer, the secondo passagio may correspond to both a resonance adjustment and a transition from the second laryngeal mechanism to the third, also called whistle voice." 

In short, this study identifies a whistle tone bridge somewhere around C5 - E5 in one soprano's voice. This is fairly in line with operatic knowledge of "the second passagio' in the female voice.