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
Musical theory came about before the concept of zero became common. So it did not occur to the music teachers that the base note might be the zeroeth note. It was the first note. Then you count the second, third, fifth, etc. And finally on the eighth note you get back to the base note. So you have an octave.
Because the eighth note is not **just** ”the first note again”. In some contexts it can be used that way, but it doesn’t have to be. You can use the eight notes to say a lot of different things, and some of them are not possible if you limit yourself to seven.
Well firstly, there aren’t seven notes, there are twelve. The science of sound is a lot more complicated than it might seem on first blush, but the answer to your question is simply historical precedent.
Music theory isn’t logical. That’s the first thing I learned when I started studying it. It’s full of stupid ways to name things, multiple names, etc. due to historical reasons. If you were starting today, you’d name things differently. Of course, I’ll get a lot of replies from musicians saying it’s all logical and reasonable, you just don’t understand it.
Because the OCTave is the EIGHTH note played when counting up most scales used in western music. If our scales all had 6 unique pitches, it would probably be called the septave.
There are generally 12 notes per octave in western music, not 7. Any time the frequency doubles or halves, it is considered to be an octave, regardless of how many notes you are dividing the scale in to, or what scale you’re using.
The major scale and minor scale each have 7 notes, but the pentatonic scale has 5 notes. There are other scales that have different numbers of notes, too, even within our 12EDO system.
Some stuff in music has funny names. You just need to accept it as it is.
Here is some music made with far more than 12 notes in an octave. The composer uses many similar note intervals so it doesn’t sound too unfamiliar, and having more notes per octave means that there are a lot more dissonant intervals, but it also allows for a lot of very different sounds and color shifts, too:
This song was made with 22 note octaves rather than 12 (noting that it isn’t just 24)
There’s a chord sequence found in this song that is a play on the jazzy II-V-I chord sequence. If you listen to the song Giant Steps next to this you might recognize it.
Back to the basics:
So while yes, the major and minor scales may only have 7 different notes – and in many musical cultures around the world there are definitely a lot that are structured in a similar way (Indian music uses a “swari” with 7 notes but they are pulled from a scale with more notes than our 12).
If you made music that only uses those 7 exact scale degrees and never picked a note that wasn’t in that scale, you’d get some pretty boring music. Music becomes a lot more interesting when it breaks our expectations a bit. Music that is all consonant may be a little bit boring. Most children’s music tends to have very few dissonances.
At least most of the time. There are exceptions for everything.
This song does have chord changes but everything was specifically picked to be very consonant. That piece of music was created with a very specific limitation in mind.
Because a lot of music theory is based on intervals. For example, a “fifth” is the interval between C and G, being the first and fifth notes of the C major scale. Similarly, the interval between middle C and the next C is called an octave, being the first and eighth notes of the scale. It is generally the distance between two notes (ie the interval) that determines how a chord or a melody sounds.
Language and maths combined sometimes seem counterintuitive, and bringing music too… Phew…
If you think about it the same way as days of the week, Monday to Monday is 8 days but there’s only 7 days in the week. So note A to note A is 8 notes in the major or minor scale, which is what the term is based upon, but there’s only seven notes in the scale.
There may be other terms for the same intonation in other cultures that don’t traditionally subscribe to the major/minor scale, however for your question it’s based on the classical scale that you hear in almost all music in the western world
The first note of each scale/key is the 1st scale degree. So in a minor:
1(a), 2(b), 3(c), 4(d), 5(e), 6(f), 7(g)……. 8(a)
“8” = “octave” (octavus in Latin)
Numerical bases aren’t really the right way to think about pitch. Assigning pitches to counting numbers implies that they are increasing linearly in some fundamental measure (they’re not) and makes it clunky or impossible to talk about the cyclicality of the pitches and their ratios. All of this comes from the fact that sound is produced by waves, and the math of waves has lots of cycles and ratios.
This means, assuming we’re sticking to some standard western scale rather than a chromatic scale or some non-western pitch system, we “count” the notes: 1 2 3 4 5 6 7 1 2 3 4 5 6 7… etc. We *could* start counting at 0, but who realistically ever starts counting at 0? The first note is… the first note. This counting system gives us an easy way to refer to the relationship between the first note and any subsequent note. Playing the first and third note is “a third”. Playing the first and fifth note is “a fifth” and so on.
Logically, this means that playing the first note along with the eighth note (which is just the first note again) could be called “an eighth,” but we use a fancy latinized term for “eighth” instead: octave. So there’s a good reason to use something related to “eight” but not necessarily a great reason to use that particular term – Enlightenment-era Europeans just love them some Latin. It has actually worked out nicely for American musicians, who refer to a half-beat rhythmic unit as an “eighth note”. It would be quite confusing if “eighth” referred to both a common tonal idea and a common rhythmic idea.
Latest Answers