Yeah… but you took away tonality - and that has caused a psychological draw, whether intended or not. Did you make that off limits because it’s a trap; or because of the reality of the importance of tonality, combined with the fact that there are nature versus nurture aspects with which one must wrestle?
I took it off because I was talking about vocal variation, and tonality is not something you can vary really When it comes to vocal variation the only fundamentals you need concern yourself with are rate, pitch and volume