Alan Greene describes singing vocal structure training as releasing the constrictors and enabling the anti-constrictors. Yoga is pose and counterpose. I’m reading a book on autism that traits as a balancing of the male and female genes, with normal in the middle.
The Taoist Yin and Yang sages must have seen these in people as well as nature. I suspect that the yin and yang has not been fully explained in the vocal structure process, and perhaps not fathomed in all its implications for modern society