That is,
VERY confusing, yes, but i think i can start somewhere on your reply..
In a full piece of music, when the piece modulates, there are two things the composer can do, is to do a double bar line and change the key signature, or to just add accidentals to make it the new key (if say, it doesnt stay in that key for long)
a deffinition of an accidental, doesnt mean 'borrowed', allthough it does 'from another key' when modulation is involved and i hope i explained that part..
An accidental is any non-diatonic note (a note not in the scale). The 'accidental' is the symbol, not the note, its the x's, #'s b's and bb's that are the accidentals...
In a minor scale (Aeolian / Natural Minor).. we have
C D Eb F G Ab Bb C...
to make it C harmonic minor.... we need (on the score) to change all the B'bs, to
B's
and this would be the accidental, its any 'marked' note with a symbol, that is changed from the original key signature.
As with changing of a key, it happens, as with using something as diatonic as the harmonic minor scale you need it..
and for say a Paganini piece that sounds chromatic, or even an Bitonal or Atonal piece, there is chromatisism, and is marked by accidentals.
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Now the modes part (i should be getting ready for my first day of work lol)
There are two ways of thinking of modes........................
1) The 'Parent Scale' way
2) The 'Structure' way
As we know everything revolves around a major scale, it is the core of modern music (yes even minor scales do)
and modes are caused by shiftin tonal centres of major scales (focusing on a root not thats not the tonic).
And this gives us a mode, now when people write modes..
say we want to compose in E Lydian.
I can take out a score, and (I use the parent scale way).. so i think, what is its parent scale. It is
B major So on the score i set out my 5 sharps, F# C# G# D# A#..
and instead of having B's everywhere in the double bass parts or F#'s to act as a dominant pedal anywhere..i use E, so what is being shown is "I am in the scale of B major, but i am focusing on E, which is the 4th mode up and therefore lydian, this piece is based on a LYDIAN scale"..
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Now the next way is the structure way, while it is still easy to think of what scale it is derived from, other people think modes sound too much the same and it comes from the way it is thought, and as '
everything is in relation to a major scale, they see as it begins with E, it starts from the E major scale, and they see, it not being a shifted tonal centre, but an altered major scale.
The key to the Lydian scale is the augmented 4th (<><>) between the root and the fourth, so classical composers would get their scores, and mark E major.. and when they right their music, E's will still be in the double bass part, to focus it on E, but instead whenever the note 'A' came up, they would mark it as 'A#'... so they see the
structure of the scale they are using, change..
Major scale = W W H W W W H
Lydian scale = W W W H W W H
so they see it as something different, not like, because B major allready has this A# incorperated into this key signature, its easier. They just like to see it as a structure of a new scale, being set out.
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To me, i think you need to know both, well over 70/80% of guitarists only know the parent scale way, and therefore they dont understand it, because its not fully in a way to understand the significance of it, in this way..
Its
Easier to work with this way, thats why it is taught in this way, but guitarists think they know it all by this way and looking at a major scale and changing the note, doesnt seem like a big change and wont be able to hear sufficiantly, the new modal sound, whilst seeing every mode compared with a major scale, you can see how many modes are related to their major scale like this..
C D E F G A B C - C Ionian [no accidentals]
C D E F G A Bb C - C Mixolydian [1]
C D E F# G A Bb C - C Lydian [1]
C D Eb F G A Bb C - C Dorian [2]
C D Eb F G Ab Bb C - C Aeolian [3]
C Db Eb F G Ab Bb C - C Phrygian [4]
C Db Eb F Gb Ab Bb C - C Locrian [5]
and as you get further away, the darker it sounds..
now every C mode has its own COMPLETE characteristic, that would never be seen if you saw everyone of these scales subcategorized in its own parent scale.
So this is why classical composers use this, but if you understand this point, then for easiness sake (like me) use the way of writing where its putting a new key signature, instead of chaning every note to an accidental to be part of the notes of the mode.
Right gotta QUICKLY get ready now!!