My musical knowledge and hearing are far from perfect, but as far as I can tell, the green verse note (on the south corner) plays a C (Do). Continuing counter clockwise, we have D, E and so, concluding with a higher octave C. Logically, the orange note (west) should play a B (Si), but I could swear it actually plays a B flat.
Oddly, if I load one of my earlier saves (one that was saved in the demo version), it seems to play a B as expected.
Any explanation for this? Will it change in future versions? Otherwise I'll be forced to uninstall the game and just play the demo - who needs to go past the energy temple when you can sing a full octave?

I would say a few words about how wonderful the game is, but mere words will never be able to fully express my awe.