Why are they called octaves if there are only seven notes?

1.14K views

The musical scales are A B C D E F G A, or Do Re Mi Fa So La Ti Do. If you do it that way, yes, there are eight. But the last note is the same as the first but at a higher pitch. If this were math, we’d basically be dealing with a base-7 system, with A or Do playing the part of zero.

So why is the set of scales called an octave if it’s all based on a base-7 system?

EDIT: Many of the first answers from when I originally asked were helpful but now I’m getting a lot of wrong answers from people who don’t seem to understand how numbers work. In a base-8 system, there are eight unique numbers, 0 through 7, after which it goes to 10. If you translate the notes into numbers, you don’t get 0 through 7, though. You get 0 through 6, after which it goes to 10 at the second Do. That’s why I was trying to reconcile that with the term “octave.”

In: 233

25 Answers

Anonymous 0 Comments

The naming is off by one because it’s primarily a naming of *intervals*. A “**second**” is the interval from the first to the **second** note in a scale (*), a “**fifth**” is the interval from the first to the **fifth** note, and so an “octave” (octo=**eight**, **) is the interval from the first to the **eighth** note.

(*) For some intervals you’ll see the prefixes “minor” and “major” used because they can have different lengths in semitones. E.g., a minor second is a semitone (such as the interval from E to F) and a major second is a whole tone (such as the interval from C to D).

(**) Many languages are still using the Latin names for the intervals such as a “quinte” for the fifth, but in English we switched to English names for most of them, only “octave” remained (and “second” which is the same in Latin and English).

You are viewing 1 out of 25 answers, click here to view all answers.