I don’t know a damn thing about music.
So take everything I say here with a grain of salt, and if you know more than I do, please feel free to set me straight.
But with the aid of the internet, I’ve started to study some music theory. Let me bring you up to date on what I’ve discovered so far. I’ll start with the topic of the musical key. I put the word “key” in italics to distinguish its sonic meaning from the mechanical key on a piano keyboard that hammers down on a particular string to make a sound. Its something I find particularly baffling, because I can’t decide whether the subject is somehow wired directly into our brains, and how we perceive sound and music, or if it is somehow culturally determined, and has evolved historically. Perhaps it it even a combination of the two?
Look at a piano keyboard. You will see a pattern of white and black keys. The black keys are in alternating groups of two and three. Each repeating pattern of black and white keys spans an octave, that is, the first key in an octave is exactly twice (or half, depending on whether you are going left or right) the frequency of the note at the other end.. Its called an octave because there are eight notes in an octave, you know, do, re, mi, fa, so, la, ti, do. However, you will note that in each octave on the piano keyboard, there are not only eight white keys, but 5 black ones. (https://recursivearts.com/virtual-piano/). As a result, there are 12 keys in an octave. Hang on, it gets better!
Go to the piano keyboard and hit a note ‘c’ it is just to the left of the first pair of black keys. If you play ONLY the white keys to the right of c (skip the black ones), you will play a musical scale spanning one octave: c,d,e,f,g,a,b,c. You will note c assumes the role of do, d becomes re, and so on till you reach the end of the octave, another c which becomes the ending do of that octave. As it turns out, each key on the piano keyboard is a half-step away from the next, (if you count both black and white keys), so though there are eight notes in an octave, there are twelve keys. Another way to say this is that there are 12 half-steps in an octave. A musical key is a subset of 8 of those keys.
We have just typed above the key of C Major, which consists of only the white keys, starting with c, to span the octave. What makes this a major key is the spacing of the intervals. C to d is a whole-step, because you skip the black key (called ‘c-sharp’). From d to e means skipping the next whole step (d-sharp). But the next key in the C-Major key is a half-step away, f. The names do, re, mi etc are assigned by their position in the key, not on the keyboard. So
the key of C-Major starts and ends with ‘do’, as do all keys.
The stepwise arrangement for all major keys is W,W,H,W,W,W,H, where the W stands for “whole” and the “H” stands for half-step. So starting out on c and following that scheme asures us that we do no need any black keys to play the C-Major key. Now, if we repeat this exercise but start with the d key, we can play the key of D-major. So now do is d, the re is
e, but the mi is f-sharp! In order to preserve the spacing arrangement of whole and half steps, we are now forced to use the black keys.
I will continue this lesson shortly, I must leave the computer for a moment