Open Music Theory
viva.pressbooks.pub
viva.pressbooks.pub
- why are there 12 notes and not any other number?
- Why certain notes sound well together (as in a chord)
https://www.youtube.com/watch?v=nK2jYk37Rlg&t=464s
(Starts at 7:44 and ends at 14:23.)
It seems like the choice of notes is due to wanting a certain amount of (mathematical) closure with octaves and fifths while also allowing for transposition.