Figure I-14. The most basic ukulele chords
for the ii-V-I progression in the key of C major. See text for details.
When investigating musical problems with
artificial neural networks, I find it useful to hear the stimuli on a musical
instrument. While I have spent a lot
time working out stimulus patterns on the keyboard of my piano, these days my
instrument of choice is the ukulele. In
this interlude I will provide the chords that I use to play the Coltrane
changes in the key of C major, developing this chord structure from variations
of the ii-V-I progression.
Figure I-14 provides the three chords that
define the simplest version of the ii-V-I progression on the ukulele. Each chord diagram illustrates the four
strings of the ukulele, and the dots on the diagram indicate the fret at which each
particular string is depressed. The
three chords that are presented are based on the assumption that the progression
involves a sequence of three triads (D minor, G major, and C major). That is, if one creates these three triads using
only the notes available in the C major scale, then one of these chords is necessarily
minor, while the other two are major (see the discussion of Figure 7-15).
The ii-V-I progression is a staple in jazz,
and using triads doesn’t provide the jazziest sound. Jazz musicians are more likely to extend the
triads used to create the Figure I-14 chords to create tetrachords. This extension, which involves adding an
additional note to each chord from the C major scale, was also illustrated earlier
in Figure 7-15. Figure I-15 illustrates
how one would play the C major tetrachords for the ii-V-I on the ukulele. Note that the D minor has now become a D
minor seventh, the G major has become a G dominant seventh, and the C major has
become a C major seventh.
Figure I-15. The ukulele tetrachords for the
ii-V-I progression in the key of C major.
See text for details.
All of the chords illustrated in Figures
I-14 and I-15 are called open position chords.
This is because at least one ukulele string in the chord is open; that
is, it is not pressed down by a finger. The
advantage of open position chords is that they generally are easier to
play. The disadvantage of such chords is
that they are special in the sense that they cannot be moved up or down along
the ukulele fret board to play the same type of chord in a different key. This makes these chords different from the
closed form chords that were the topic of the previous interlude “Ukulele
Chords and Perceptrons”. Our next move
is to transform the Figure I-15 progression into one that uses closed position
chords.
In order to perform this transformation, we
will use two different tricks. The first
is to replace the Dm7 and Cmaj7 chords with alternative fingerings that can be
found in a decent ukulele chord book (Johnson, 2005). For these two chords we
pick two fingerings that are related; both are barre chords that involve pressing
the index finger down across all the strings at the fifth fret.
The second trick is to take advantage of
chord substitution. In general, jazz musicians
see a chord’s name as an indicator of potential chords. For instance, when such a musician sees that
a G7 is the next chord, they would feel perfectly comfortable with substituting
a different, but related, chord. Chord
substitution conventions permit G7 to be replaced, for example, with G9 or with
G13 in order to add musical variety. We
will choose the G9 chord because the barre form of this chord places it in a similar
position on the fret board to the other closed form chords in the ii-V-I, as is
illustrated in Figure I-16.
Figure I-16. Closed form ukulele chords
for the ii-V-I progression in the key of C major. See text for details.
There are three important points to make
about Figure I-16. First, the particular
chord choices that it illustrates begin quite a bit further down the fret board
(at either fret 5 or 4) than was the case in Figures I-14 or I-16. Each chord diagram has a number on the left indicating
the starting fret, and the chord diagrams have been extended more than is
typical to show where on the ukulele each chord is being played.
Second, the G9 chord that is illustrated is
not likely to be found in many ukulele chord dictionaries. This is because this form of the chord does
not include the root note G. Instead, it
uses the other four pitches that are part of G9. These four pitches actually define a minor
seventh (flat fifth) chord in a different key.
G9 as illustrated in Figure I-16 is also Bm7♭5.
Third, because these three chords are all
in closed form one can move these patterns up or down the fret board to play
the ii-V-I progression in a different key.
For instance if one uses the same chord patterns illustrated in Figure
I-16, but moves each upwards a fret (towards the top of the page), then the result
is the ii-V-I progression in the key of B major.
As detailed in Chapter 9, the Coltrane
changes elaborate the ii-V-I progression by using the same three chords in Figure
I-16, but also adds four additional chords that serve as lead ins. We can create the Coltrane changes by adding
these four chords to Figure I-16, attempting to choose closed form chords that
minimize movements along the fret board.
The Coltrane changes for the ukulele in key
of C major are presented in Figure I-17.
Each chord is a barre chord, meaning that this figure defines chord patterns
that can be shifted to different fret board positions to generate the Coltrane
changes in a different key. For example,
shifting each chord a fret downwards (towards the bottom of the page) produces this
progression in the key of C# major.
Figure I-17. Closed form ukulele chords for the Coltrane
changes in the key of C major.
Similarly, Figure I-17 raises the possibility
of generating alternative versions of the Coltrane changes for ukulele. For instance, might easier chord fingerings
emerge if one explores chord substitutions for the other dominant seventh
chords in the figure?
References
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