Common polyphonic vocal sounds

My question is what are some common well known polyphonic vocal sounds, how do they differ and what does the community call them?

I've gotten good at two inward poly sounds, one more nasal higher pitch (the one TwoH uses, nasopharynx?) and one lower pitch (orthopharynx?).

Outward poly that Stitch and Pacmax use seems extremely difficult for me in comparison. Im curious about your thoughts.