... and why did we in the west end up with a 12-note scale? 12 equal divisions of the octave lets you approximate a lot of the interesting ratios 2/3, 3/4 etc (only approximate, see 'even tempered') without the notes being too close together. I think I read the next optimum division would be to divide the octave into 43, but then you're getting far too muddy.
... and if its 12 equal semitones, why have some of them got proper names (CDE) and some treated as variants (sharp/flat). Or in other words, why the white keys and black keys on the piano?
Well lets take the 'foundation' note of your piece of music - this would, more or less, be the note that gets involved the most, although its a bit more complicated than that. Building from that note, and lets say we've chosen C to make things simpler, if you wanted to choose other semitones from the 12 available that would let you build lots of nice ratios starting from C and the note thats 3/2 above it which would be G, then you more or less end up with the white keys on the piano, and you leave the black ones out (mostly). Thats called the C-major scale. There's also a minor version where you choose slightly different semitones to get a 'sadder' sound, and thats C-minor.
The names of the notes (CDEFGAB) are the white keys on a piano are based on the C-major scale, with the sharps and flats defined in relation to them. Some sort of legacy naming convention that is now baked into musical notation at the lowest level and makes everything much less clear than it should be. Because it you want to transpose up or down and use a different foundation note (as happens literally all the time) then you have to use a mix of notes with proper names CDE and the sharps and flats (a mix of white and black piano keys) and thats when it gets confusing. Well, unless you know what you're doing I suppose, and then its not confusing.
In summary: the major and minor scales are kindof optimum selections of notes from the 12 available to make your song sound fairly good. Like a kindof best practice.
But the names of the notes are ridiculous. Its as if instead of the digits 0123456789 we had some weird number system where 3 didnt exist and we called it '4 flat' and 6 was replaced by '5 major' for no good reason.
... and if its 12 equal semitones, why have some of them got proper names (CDE) and some treated as variants (sharp/flat). Or in other words, why the white keys and black keys on the piano?
Well lets take the 'foundation' note of your piece of music - this would, more or less, be the note that gets involved the most, although its a bit more complicated than that. Building from that note, and lets say we've chosen C to make things simpler, if you wanted to choose other semitones from the 12 available that would let you build lots of nice ratios starting from C and the note thats 3/2 above it which would be G, then you more or less end up with the white keys on the piano, and you leave the black ones out (mostly). Thats called the C-major scale. There's also a minor version where you choose slightly different semitones to get a 'sadder' sound, and thats C-minor.
The names of the notes (CDEFGAB) are the white keys on a piano are based on the C-major scale, with the sharps and flats defined in relation to them. Some sort of legacy naming convention that is now baked into musical notation at the lowest level and makes everything much less clear than it should be. Because it you want to transpose up or down and use a different foundation note (as happens literally all the time) then you have to use a mix of notes with proper names CDE and the sharps and flats (a mix of white and black piano keys) and thats when it gets confusing. Well, unless you know what you're doing I suppose, and then its not confusing.
In summary: the major and minor scales are kindof optimum selections of notes from the 12 available to make your song sound fairly good. Like a kindof best practice.
But the names of the notes are ridiculous. Its as if instead of the digits 0123456789 we had some weird number system where 3 didnt exist and we called it '4 flat' and 6 was replaced by '5 major' for no good reason.