Why is the musical scale the way it is? 12 keys: 7 major, 5 minor?
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If you play a note that is not a pure sine (which we couldn’t easily make until more recently), there are certain additional resonant frequencies that usually are also present to a degree. The most common is the fifth, this is the jump from C to G. Playing just the fifth gives you punk rock power chords. Ok so you have a second note, if you take the fifth of THAT, you get D. Continue this process and you get the circle of fifths, which ends up hitting all of those notes you mentioned.
Because some dudes decided it sounded good, and we in Western society agreed. Literally that’s it. There’s nothing special about it aside from that’s what we’re used to.
We also have more scales than you describe, and they all sound different with their own flavors.
What do you mean ‘7 major, 5 minor’…?
I’m assuming you mean 7 white notes, 5 black notes
In western music, we use the major scale as the basis for our music. It consists of a pattern of whole steps and half steps (whole whole half whole whole whole half), 7 notes in total. The keyboard is designed so that all the white notes correspond to a major scale (C major, specifically). Because there are 5 whole notes, they need to be filled in with one black note each so all 12 divisions of the octave are achieved. This way, a major scale can be played starting on any note, since any major scale other than C major will require at least one black note
There are major and minor keys based on all 12 notes, not 7 major and 5 minor – where did you get that?
We get our 12 tone system from physics – partially. You can sort of get all 12 notes by multiplying a pitch’s frequency by 3/2, 12 times. Although it doesn’t quite work out so nicely, so we’ve made some compromises over the years. The major and minor scales (the basis of keys) are subsets of 7 of the 12 tones. They were chosen over history because people like how they sounded, but there are other scales/keys that exist, you just don’t hear them a lot.
This applies to western (European) music only.
This is a rabbit hole question. Like how does calculus work. So you want to know where do notes come from?” Start with “what are overtones and harmonics?” Then listen to Mozarts concerto for natural horn no 4 rondo. It is played on a single length of tubing (no slides like a trombone or valves to change the length of horn.)yet can play all the notes Mozart needed it to. Kind of like frets on a guitar but not exactly. Here’s the best video I could find
The naming and conventions (like black and white keys) are created by humans but there are fairly simple “natural” reasonings for the way much of the world’s music is created.
Sounds are essentially vibrations and things in nature vibrate in certain ways. The simplest thing to start with is a string stretched and plucked.
The loudest note is the fundamental frequency and there will be softer notes that are produced. These sound “nice” to us. These “nice” notes will be in simple ratios of the fundamental note frequency. So these ratios are 2:1, 3:2, 4:3, 5:4, 6:5, 5:3 etc. These collection of ratios form the basis of musical notes. For modern instruments, these are adjusted slightly to make instruments easier to tune and play along each other.
The current system of 12 notes allows music to be easily scaled up and down and still sound “nice”. Nearly all music is written to use a smaller subset of these notes. So music written in a major diatonic scale (do, re, mi..) will use 7 of these 12 notes predominantly. Music written in a pentatonic scale (a lot of Chinese and Indian music) uses 5 notes from this scale. Traditional “blues” music is also generally pentatonic.
Western music is all math. Scales in Western Music come from Pythagoras, the triangle guy.
If you pluck a string, it makes a sound. If you pluck a string half the length, it vibrates twice as fast back and forth, and makes a sound that is exactly one octave higher. Other simple ratios work together, too.
Here’s some songs you probably know, and the interval *in their first two notes*, and the ratio of the frequencies between the notes.
A full octave = 2:1, like from Somewhere Over the Rainbow.
A ‘perfect fifth’ = 3:2, like Twinkle, Twinkle, Little Star or the ABC’s song.
A ‘perfect fourth’ = 4:3, like the Wedding March.
A ‘major third’ = 5:4, like Oh When the Saints go Marching In.
All the notes in the scale come from these. The intervals in the major scale are usually simpler than the minor scale. If you are talking about the notes in the C major scale (all the white keys on the piano – 7 notes), then the ‘black notes’ (the other 5) come from more complicated intervals. For example, a minor 7th (the start of the original Star Trek theme) is about 16:9.
So if you collect all the notes in a scale that have ‘nice’ or ‘simple’ intervals, you get a total of 12 notes.
Fabulous fact: if you try to use these ratios exactly, you can find that things don’t work as you expect. So instead of using these ‘justly tuned’ ratios, you can use a different way of tuning that ‘averages out’ the differences. Your piano, and most wind instruments use tuning like this. It gives slightly different results that sound good, without the problems that the ‘simple ratios’ can give.
Ask me anything?
Bobby McFerrin didn’t so much explain as demonstrate this in a cool way
First: why is it 12 and not 13? Because if you use notes with integer harmonics (as most instruments do) and do the math trying to determine how to subdivide an octave into equal parts, 12 is a comparatively very low dissonance number. It also allows the neat 2^(19) ≈ 3^(12) approximation, so 12 fifths is approximately 19-12=7 octaves.
Second: why the arrangement of white keys? That one is more “cultural” – probably because the circle of fifths goes F-C-G-D-A-E-B. If you use only the black keys, that’s also a pentatonic scale, but Western music usually uses 7-tone scales.
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