Introduction to
Modulation
By Raphael Crystal
It is sometimes necessary to
move from one key to another in the course of a piece. This kind of harmonic
motion is known as “modulation.” It should not be confused with transposition.
While transposition involves taking a tune written in one key and playing it in
another, modulation is the process by which you arrive at the new key.
Modulation is often useful
when you are accompanying a singer or group of singers. Imagine you are
accompanying the song, “My Country Tis Of Thee” in the key of F major. Our
first example shows the last four bars of the tune:
Measure 1
F/CFA
E/CGBb
F/CFA
G/BbCG
A/ACF
Measure 2
F/CFA
G/CEBb
A/CFC
Measure 3
Bb/DFBbD
C/CFA
C/BbEG
Measure 4
F/ACF
For the last verse, to provide
some variety, you might want to move to a new key. Typically, the move is up a
half step. This doesn’t strain the singers’ ranges much, but it provides a
bright, new sound. Here are the first four bars of the tune in the key of F
sharp major:
Bar 1
F#/A#C#F#
D/A#D#F#
B/BD#G#
Bar 2
C#/BC#E#
D#/B#D#F#
E#/BC#G#
Bar 3
F#/C#F#A#
D#/D#F#A#
B/D#G#B
Bar 4
C#/C#F#A#
Double SharpC/BE#G#
D#/A#D#F#
The problem is how to get
from the end of the tune in F major, as shown in our first example, to the
beginning of the tune in F sharp major, as shown in the second example. This is
an harmonic problem, which calls for an harmonic solution. The strongest, most
direct harmonic movement is from a “dominant” chord (the chord built on the
fifth degree of the scale) to a “tonic” chord (built on the first degree). This
is known as a V-I progression. A dominant seventh chord may also be used, and
this is called a V7-I progression.
To move from F major to F
sharp major, we can use the dominant chord of the new key to point the way. Our
next example shows the last two bars of “My Country ‘Tis Of Thee” in F major.
After the final note, a C sharp chord has been inserted, which is the V chord
of F sharp major. This establishes the new key, and the example concludes with
the first two bars of the tune in F sharp major. The C sharp chord and the F
sharp chord that begin the tune form a V-I progression. A little melodic phrase
has also been added to guide the singers to the first note in the new key.
Measure 1
Bb/DFBbD
C/CFA
C/BbEG
Measure 2
F/ACF
C#/C#E#C# to B (V)
C#/A# to G#
Bar 1
F#/A#C#F# (I)
D#/A#D#F#
B/BD#G#
Bar 2
C#/BC#E#
D#B#D#F#
E#/BC#G#
If, instead, we want to move
up a whole step to the key of G major, we can use a D chord, which is the
dominant in that key. Or, as in our next example, we can use a D7 chord so the
progression is V7-I. Again a melodic phrase leads to the opening note. Notice
that in both of our examples the modulation has been achieved without adding
extra bars to the tune.
This is the neatest way to do
it:
Measure 1
Bb/DFBbD
C/CFA
C/BbEbG
Measure 2
F/ACF
D/CDF# to G = D7 (V7)
D/A to F#
Bar 1
G/BDG = G (I)
E/BEG
C/CEA
Bar 2
D/CDF#
E/C#EG
F#/CDA
We have been discussing the
simplest form of modulation. In more complicated modulations a group of
transitional chords may be involved, but almost always the dominant chord of
the new key plays a major role.
If you would like to gain
facility in modulation, you should become familiar with the V7-I progression in
all keys. Our final example provides a pattern that can be extended up through
all twelve tonalities. Practice it until it becomes automatic. When all of the
dominants are (literally) at your fingertips, you will be ready to move the
harmony in any direction.
C Major
GF/BDG = G7 to CE/GC = C
Db Major
AbGb/CebAb = Ab7 to DbF/AbDb
= Db
D Major
AG/C#EA = A7 to DF#/AD = D
Eb Major
You might want to invest in Instant Transposer Software
"Jazz washes away the dust of every day life." -- Art Blakey