The fact that music tends to be written around eight note scales with uneven spacing between them seems very arbitrary. I suppose there's a mathematical origin to it, but it seems strange.
@Rosemary *nods*
I haven't done the research, but I think it comes down to these scales giving us a good selection of consonant ratios of note frequencies, and simple ratios like 2:3 or 3:4 sound good? And, like, historical accident of what worked for musicians in the western tradition as they built on what people had done before ended up settling on this as a useful tool for making music.
@packbat Since Eastern music, as far as we're aware, also fits into the same pattern of notes, I think there's something deeper than just historical accident, unless it goes all the way back to the indus valley civilization or something. I'm not sure if Native American music does as well, though. I don't know if we've ever heard any Native American music, actually.
@Rosemary ...!
You know that 12tone channel Felthry talked about the other day re: defining music? Apparently they put out a whole video on why people favor the I-guess-they-call-it-seven note scale yesterday: https://www.youtube.com/watch?v=6wCfmgRJAbM
@Rosemary I don't know much about music outside the western tradition, but I could believe there are some pretty substantial mathematical reasons in there somewhere for some of the commonalities. Like, Pythagorean tuning constructs all its notes out of ratios of 2:3, moving up and down octaves (ratio of 1:2) as necessary - https://en.wikipedia.org/wiki/Pythagorean_tuning - and that ends up producing about 12 usefully distinct notes per octave. And our modern scales select from those 12 notes per octave.
...I'm sure people have written usefully about this, but I haven't tried to go looking for it.