Which Came First, the Voice or the Personality?

I was observing two of my JTEs in classes today. One has a command and presence, not to mention a kick ass personality. The other has an obvious nervousness and the personality of a used Kleenex.

The strong one has a voice that is lower in pitch (but still feminine) and resonates with confidence. The students and I respect her. The feeble one has a voice that is high pitched and wavers. The students and I respect...not so much.

If one is walked upon by students on a daily basis, I suppose it would make sense that her voice is high-pitched. But is it high pitched because she’s been walked on? Or does she get walked on because it is high-pitched?

What is the correlation between voice and personality? If voice is physiological, are our personalities pre-determined, if you will, by our voices? …OR do our personalities create our voices? Does a weak voice cause a meek personality? Or does a meek personality cause a weak voice? I’ve never met a person with a high pitched voice and a magnetic personality.