Learn to improvise. 2004-2005. Lesson 03: harmony in groups of three chords.
The harmony changes continuously, but remains for a while within an
area of three chords, called a key. As the keys during a piece of music
change, they are called temporary keys. This way you can distinguish
them from the initial key, which is indicated at the beginning of a staff
in staff notation.
This thinking in groups of 3 chords is very important and is common
in the world of music, but seldom expressed in this simple way. I will
call them the three main chords of a key. Their root notes are on the
1st, 4th and 5th notes of the scale (for C the scale has the white keys and
the 3 root notes are c, f and g) and consequently the 3 chords are
indicated by I, IV and V. I is called root, V is called the dominant
chord and IV subdominant chord. The scale of a key consists of all
the notes of the three main chords in a row (e.g. the main chords of the
key of C are the chords C, F and G and all the notes of them in a row are
the white keys c d e f g a b).
In practice the dominant chord is often played as seventh chord and
then called dominant seventh chord. The reason this is possible is
because the seventh note (the note two key steps left of the root note of
a chord, e.g. G = g+b+d and G7 = g+b+d+f) belongs to the scale of C
(the seventh note of G7 is f, which is also a white key). The seventh
notes of I and IV does not belong to the scale, in other words does not
belong to the key.
Changing from one key to another is called modulation and is an
important moment in the harmonic stream. Take care you don't falter
on that very moment! Those moments are treacherous, as they are more
difficult than a stream within a key and moreover have a climax.
Initial G and a climax with temporary key Am.
In a chord scheme never is indicated where the modulations are. You
have to feel yourself when a key changes and to which one. For
improvising this must be known beforehand, because you have to know
which notes belong to the scale and which notes not.
Actually this thinking and working in groups of three chords, so in keys,
respectively in scales, is the basis of this course. That's why I advise to
start making improvisations in only one initial key, say C, so with the
chords C, F and G(7), in order to learn what a key means and what the
effect is in a melody of notes which belong to the scale and of the other
ones.
When you start working with chord schemes running through different
keys, it is handy to write those keys on the right place in the scheme (by
color, by brackets, in another kind of character or the like). After a
while you recognize these modulations automatically if you always play
with the same initial key. It is practical to consider tones not belonging
to the scale as treacherous.
E.g. In the scheme C D7 G7 the initial key is C and the scale is c d e f g
a b. During D7 the key is modulated to G and the scale has become g a
b c d e f#. At this moment note f does not belong to the temporary scale.
It is tricky as it has belonged to the valid scale just a moment ago (when
the key was C). So you are inclined to interpret it wrongly (out of tune).
1st example has note f# during D7, the 2nd
example note f.
Actually it is more complicated, because the place of the key in the
chord scheme also has influence on the other notes of the melody note.
E.g. consider note e-flat in the previous example. During key C it has
a jazzy effect, but keeps on having that in key G (during D7).
Note e-flat is jazzy in C but also
in G (during D7).
We would expect the jazzy note in key G to be the note b-flat. Well, it
has a jazzy effect but in a different way.
Note b-flat is jazzy too during D7 but
in a different way than e-flat.
HOMEWORK:
Improvise as in the homework of lessons 01 through 04
of the previous year. Transpose all the songs you use for improvisation
to one initial key (C is easy to understand, G sometimes easier to grab).
Don't play the first years in different initial keys.
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