Why is the musical scale the way it is? 12 keys: 7 major, 5 minor?
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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.
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