Modulation – moving from one key to another – occurs in many forms of music. In classical music, it is often an important dramatic feature, and is a structural element in certain musical forms (especially sonata and rounded binary form). Like modulation, tonicization implies another key as a tonal center; the difference is that a modulation is confirmed through a cadence in the new key. A key or chord may be tonicized in the middle of a phrase, with no cadence to confirm it as a modulation.
There are two basic methods of modulation: pivot and direct.
- A pivot modulation is found in the middle of a phrase when one harmony or a single pitch is “reinterpreted” to function in each of two keys.
- A direct modulation tends to be found when a new phrase suddenly begins in a new key. There may be one or more turnaround chords (explained below) that soften the transition between keys. Turnarounds are not technically “pivot chords” since they do not occur in the middle of a phrase.
Modulations between closely-related keys (those with key signatures that differ by no more than one accidental) sound more subtle than modulations between distantly-related keys because such keys share more tones in common. For instance, The closely-related keys to C Major are F Major (the subdominant), G Major (the dominant) and A Minor (the relative minor). The minor relatives of the subdominant and dominant keys (D Minor and E Minor, respectively) may also be considered to be closely related to the main key, but in classical practice are not commonly found as destinations for modulation.
Procedures: In detail
- Direct modulation. A direct modulation occurs when no common chord is used. It can be found during the course of a phrase or “between phrases” when a new phrase begins without harmonic preparation in a new key. Sometimes the abrupt effect of a direct modulation between phrases is made gentler through the use of turnaround chords. Examples: Schubert’s “Arpeggione Sonata” and Rodgers & Hart’s “Have You Met Miss Jones.”
- Pivot modulation. This method is found within the passage of a phrase: the phrase begins in one key and ends in another. To locate a pivot chord, find the first harmony that does not belong in the previous key. This will require the use of an accidental. Go back one harmony: if that chord is diatonic to both the old key and the new one, it is the pivot chord. One major exception is if the first chromatic chord is a dominant of the new key and it is preceded by its cadential six-four. In this case, the cadential six-four is part of the new key, so the pivot chord will precede it.
- In a pivot modulation by common chord one chord common to both keys is used as a pivot chord. For example, when modulating from C Major to G Major, an Am chord might work as a pivot because it can simultaneously function as vi in C and ii in G. Here are two more detailed explanations of common-chord pivot modulations: <from artofcomposing.com> and <lotusmusic.com>. Note that the artofcomposing.com page explains “altered common chord modulations,” which are what I call “pivot modulation by chord-quality shift” below. Examples: “O Canada” and Schubert’s “Arpeggione Sonata.”
- A chromatic pivot chord may be used in remote modulations where there is often no true “common chord” to use as a pivot. For instance, in The Beatles’ Lady Madonna, the C chord is used as tonic in C Major and ♭III in A Major.
- A pivot modulation by common tone sometimes is found between distantly related keys when a common chord is not used. The common tone will often bind chords that share a chromatic third relationship (roots are a third apart, but not diatonic). Sometimes a common tone or common chord modulation will involve the enharmonic respelling of one or more notes at the point of modulation; this is called an enharmonic pivot modulation. Examples: Beethoven’s “Waldstein Sonata mov. 2” and The Beatles’ “Penny Lane.” Another example from the Beatles is here.
- Pivot modulation by sequence (“sequential modulation”). A sequence is a musical unit with two basic features: a melodic gesture that is repeated progressively higher or lower (usually up or down by step) and a harmony pattern that moves along with the melody. Wikipedia has a pretty good explanation of it. In such patterns, sometimes chords occur that do not function clearly in either the starting or ending key of a modulation. In this case, the modulation may be understood as a modulation by sequence. Most sequences that modulate, however, can be easily labeled as common chord modulations. Example: Antonio Vivaldi: “Spring” mov. 3 bars 29 & 30.
- In a pivot modulation by chord-quality shift, a diatonic chord is used before a note is added or chromatically changed, altering its function and moving the music to a new key. This is more like a common-tone modulation than a common-chord modulation; in this case, the common tone is the chord root.
- Shift from tonic chord to dominant 7th. When changing the quality of the tonic chord from major or minor to dom7 (Mm7), a phrase can modulate by creating a dominant 7th chord over the tonic. This means of modulation is most often employed to modulate from the dominant key back to the tonic, or to the subdominant (as a dominant 7th built on the tonic leads to IV). Example: Franz Schubert Sonata for Arpeggione
- Shift from major chord to +6. Augmented sixth chords built out of a major chord can be used to modulate: their tendency tones (♯^4 and ♭^6) point to ^5 in the destination key. Since the bass note is often ♭^6, the bass resolves down by half-step and leads to a new dominant, which is confirmed by a cadence in the new key. In the example given, Beethoven builds a German +6 on A♭ in bar 29, which progresses to I6/4 in C Major. (Note that the German +6 is enharmonically identical to A♭7, softening this transition.) Example: Ludwig van Beethoven: Symphony No. 5, mov. II bars 23-31.
- Shift from major chord to minor (or vice-versa). Example: Franz Schubert: Der Wegweiser bar 16
Tonicization typically refers to a weak reference to a new key during the course of a phrase. It is not as strong as a modulation because tonicizations do not cadence in the new key. If there is a cadence in a new key, it is a modulation, not a tonicization. There in no consistent way to label tonicizations; in this course, we label them in the same manner as modulations. Example: Rodgers & Hart: Have You Met Miss Jones? bars 10, 18-24 & 26.
Note: Sometimes, the dominant is tonicized just before a half-cadence. This is not considered a modulation. Since the music continues in the same key, we label this chord as a secondary dominant. Example: Robert Schumann: The Happy Farmer bars 1-9.
The term turnaround is most frequently found in a jazz context, but the concept can be applied to much music. It refers to a chord or series of chords that occur after a cadence chord, either creating musical “motion” through chord changes that remain in the key of the cadence (often a repetition of the ii-V pattern) or that provide the quick tonicization of a new key that will begin the next phrase via direct modulation. Sometimes a turnaround chord simply changes the quality of a tonic chord to dom7, helping to progress to the subdominant chord or key. Example: Rodgers & Hart: Have You Met Miss Jones? bar 24.
How to label modulations
Use capital letters to indicate major keys and lower-case letters to indicate minor keys.
To label a direct modulation, simply label the new key under the beat where the new key begins. After this point, Roman numerals should be adjusted to reflect the new key.
In a pivot modulation, show how the pivot chord functions in each key by stacking the Roman numerals vertically, clearly showing to which key each Roman numeral belongs. Continue to label chords in the new key, indicating with a key name that this is occurring.
How to find out if and how the key has changed
The best way to locate modulations is to compare the starting key of a phrase with its ending key (the key of its cadence). Remember that cadences don’t always end on tonic chords — don’t identify a half cadence, for instance, as a modulation to the dominant key. It’s usually easiest to find out when a modulation occurs by ear and then study the music to find out when the key shifted and what the procedure was.
To help practice finding and identifying modulations, I’ve created these articles: