Music Theory, notation, and nasty modulating key changes

[GorillaMan]

@1920s Style "Death Ray"

But isn’t it E minor that is part of the A minor key, not E major?

No, it is E major which is part of the key of A minor, even though following the key signature alone does create E minor. To describe something as being in a major or minor key, one essential element is the relationship between chords V and I, and their ability to close phrases (sections, whole pieces) with perfect cadences. Without the sharpened seventh degree of a minor key, the whole aural effect of such cadences disappears entirely, and the sense of harmonic finality and unambiguity they offer is lost. The result of this is that it no longer sounds like A minor.

To put it another way, which my pupils hear countless times: ‘Chord V is always major. It just is. Otherwise it sounds wrong.’

[Musicat]

@Eureka

So the issue I’d like more information/informed speculation on is this: How do composers/arrangers decide where the key change goes, do arrangers ever write the key change before the nasty modulation stuff (rather than after) and do arrangers ever position key change markings in music to facillitate dividing the music into sections–so that what appears immediately post key change is the next repetition of the melody/chorus whatever rather than 3 measures of transitional stuff before the key change?

In traditional music, the key change is considered to be where the new tonic starts or has been defined. This usually happens where the new part “starts”, like the downbeat to the new chorus, verse, or whatever.

This works pretty well except for some avant garde music where the tonal center never gets established in the sense that I - IV - V - I defines it in 18th Century harmony or modern pop music.

Everything leading up to the actual signature change is considered modulation or a transitional harmony. While a case might sometimes be made that changing the sig earlier will eliminate some accidentals, theorists (like me) probably wouldn’t like it. Written music is often a mix – a compromise between the theoretical and the practical.

[Richard_Pearse]

@GorillaMan

No, it is E major which is part of the key of A minor, even though following the key signature alone does create E minor. To describe something as being in a major or minor key, one essential element is the relationship between chords V and I, and their ability to close phrases (sections, whole pieces) with perfect cadences. Without the sharpened seventh degree of a minor key, the whole aural effect of such cadences disappears entirely, and the sense of harmonic finality and unambiguity they offer is lost. The result of this is that it no longer sounds like A minor.

Thanks (to pulykamell too), I have enough knowledge to understand your answers, but not enough to know what I don’t know!

[Eureka]

Musicat,
Thanks. Your post, combined with the suggestion above that sometimes modulating involves notes which aren’t really a part of either key involved, make sense of this issue for me.

ETA: I mean, this thread was inspired by a transition in a particular piece of music, but the transition itself isn’t that different from transitions I’ve encountered before. So I was curious about the general principles.

[Zebra]

As to the OP.

You’ve probably noticed that a musical work is divided into sections.

Sometimes they are marked with a large letter, to make it easier to just say, “let’s start at letter D”. Usually a work is divided into groups of 8 or 12 or 16 bars.
The key change is usually marked at the start of one of these sections. (not always but usually)