I’m referring to the name. What relation does it have to eight?
Eight notes: C D E F G A B C. (People used to not know how to count properly.* I think it comes from not having a clear concept of zero.)
* One can argue that this counting system is no worse than ours, but to do so, one would have to explain why ten octaves is seventy[one] notes.
Similarly, other musical intervals—i.e., ratios between frequencies—have names that are all arguably off by one. A “perfect fifth” is, e.g., from C to G. C,D,E,F,G: five notes. So a fifth plus a fifth is (not a tenth but) a ninth.
I’m referring to the name. What relation does it have to eight?
Eight notes: C D E F G A B C. (People used to not know how to count properly.* I think it comes from not having a clear concept of zero.)
* One can argue that this counting system is no worse than ours, but to do so, one would have to explain why ten octaves is seventy[one] notes.
Similarly, other musical intervals—i.e., ratios between frequencies—have names that are all arguably off by one. A “perfect fifth” is, e.g., from C to G. C,D,E,F,G: five notes. So a fifth plus a fifth is (not a tenth but) a ninth.