The horizontal dotted lines denote the forced tones.

The upright dotted lines denote the limits of the registers.

The cones < denote the volume of tone in each register at any given point.

The horizontal dotted lines denote the forced tones.

The upright dotted lines denote the limits of the registers.

The cones < denote the volume of tone in each register at any given point.

Interesting!

Interesting thoughts about cones. Years ago, I began to think of pitches as cone shaped. You hear the sound with the center of the pitch having some depth. When the pitch is out of tune, the sound is 2 dimensional.