Changing keys is a great way to add energy and interest to music but how does one get from one key to another?
First, a little bit of theory…
Tonic defines the key. Tonic is the stable "home" or "done" note or chord that's built on the first note of a scale e.g. in the key of C major, C is both the 1st scale degree and the name of the I chord.
The dominant (or V7) is the chord that is built on the fifth chord of a scale. It has a restless unstable quality that wants to resolve back home to tonic.
Five Modulation Techniques
1. Direct modulation
The easiest way to change keys is to just do it all of a sudden with no modulation. This works especially well with key changes that are a whole or half step apart. If the tune has pick up notes such as Oh, When the Saints Go Marching In, start those in the new key. Tip: Once you arrive in the new key, vamping the chords a bit before the melody returns is one way to make the transition less abrupt.
2. Change Modality
Moving from a major key to its parallel minor key or vice versa (e.g. C major to C minor), also works well to just do it without a modulation. The ear readily accepts this change because the tonic note remains the same and both keys have the same V7 chord (e.g. G7 is the V7 chord in both C Major and C minor conventional harmony). Go Tell Aunt Rhody is a one such example.
To modulate from key of D major to the key of D minor and vice versa:
D Major key > A7 chord > D minor key > A7 chord > D Major key.
3. Pivot chord modulation
Some key changes sound better if they are preceded by a pivot chord to smooth the transition. The pivot chord that most often precedes a key change is the V7 of the coming new key.
To modulate from key of C major to key of F major:
C Major key > C7 chord (V7 of F major) > F Major key
To soften the modulation further, precede the V7 of the new key with its own dominant preparation chord (IV and ii7 are most common) of the new key.
To modulate from key of C Major to key of G Major:
C Major key > Am7 chord (ii7 of G Major) > D7 chord (V7 of G Major) > G Major key
Tip: This works especially well when both keys share a few chords. For example, the chords, G and Em7 are in both keys of C major and D major so the ear accepts the transition more readily.
4. Gradual modulation
This one involves preparing the ear for the new key by gradually introducing notes into the melody from the coming key signature. The result gently prepares (some would say "confuses") the listener's sense of the tonal center so the key change feels seamless. This is a common strategy in Sonata form. Examples include: Mozart: Piano Sonata No. 16 in C major (Sonata Facile), K. 545 or Sonatina in C, Opus 36 No. 1 by Clementi. Both begin in C major and quickly and seamlessly modulate to G major in this way.
Like going up stairs, sequencing involves systematically moving around (usually up) a little portion of the melody and its associated chords until the new desired key is reached.
To modulate from key of C Major to key of E Major:
Repeat third measure up a whole step and then continue melody up another whole step.
Bonus: Pop Dominant Chord
Here's a more contemporary sounding way to change keys. It's similar to the V7 pivot chord modulation but it has a twist. Instead of preceding the new key with its V7 chord, play the IV chord of the new key over its 5th scale degree in the bass.
To modulate from key of C Major to key of A Major
C Major key > D/E (IV of A Major over 5th scale degree) > A Major
Happy modulating and until next time, enjoy your creative music making journey!