Advanced Modulation (Off to Remote Key Areas)

4.5.1Introduction: Beyond the Horizon

Modulation - the process of changing the tonal centre of a piece of music - is one of the most powerful dramatic tools available to a composer or songwriter. As we saw in earlier chapters (such as Chapter 2.4 (Primary Chords)), moving between closely related keys (like from C major to G major, or C major to A minor) is relatively straightforward. These keys share most of their scale notes and many of their diatonic chords, allowing for smooth, nearly imperceptible transitions.

But what happens when the music needs to travel further? What if the narrative arc of a song demands a shift from C major not to a friendly neighbour, but to a distant, unrelated key like E♭ major or F♯ minor?

These are remote key relationships. Keys are considered remote or distantly related when their key signatures differ by three or more accidentals. Because they share very few (or zero) common chords, we cannot rely on simple diatonic pivot chords to bridge the gap. Instead, we must employ advanced modulation techniques: chromatic pivot chords, enharmonic reinterpretation, sequential modulation, and the sheer brute force of direct modulation.

Let's explore how composers and songwriters navigate these distant harmonic waters.

4.5.2Direct, Abrupt, and Phrase Modulation

Sometimes the most effective way to enter a new room is simply to kick the door down.

Direct modulation (also known as abrupt, shift, or phrase modulation) occurs when the music changes key without any transitional chords preparing the ear for the shift. The music simply stops in one key and immediately starts the next phrase in a new key.

This technique is frequently used at natural sectional boundaries in a song - for example, moving from the verse into the chorus, or from the bridge into the final choruses. Because there is no pivot chord to soften the transition, the effect is sudden and dramatic. It forces the listener to immediately reorient themselves to the new tonal centre.

The most famous (and sometimes infamous) application of direct modulation in pop music is the Truck Driver's Gear Change. This is the classic step-up modulation, where the entire song simply shifts up a half-step or whole-step for the final chorus to inject a sudden burst of artificial energy.

You can hear this unapologetic shift in Whitney Houston's I Will Always Love You (shifting up a half step for the final choruses), Michael Jackson's Man in the Mirror, and Bon Jovi's Livin' on a Prayer. (For a deeper look at how Bon Jovi's modulation interacts with the song's overall structure, see Chapter 4.8 (Advanced Form)). While critics sometimes deride the step-up modulation as a cheap trick or a cliché, when executed with conviction, it remains one of the most surefire ways to elevate the emotional intensity of a pop arrangement.

4.5.3Chromatic Pivot Chords

When we want to move smoothly to a remote key, we need a pivot chord - a chord that functions logically in both the old key and the new key. However, because remote keys share no diatonic chords, we must use a chromatic pivot chord.

A chromatic modulation occurs when a chromatically altered chord (such as a secondary dominant or a borrowed mixture chord) is used to bridge the two keys. The chord is diatonic in one key, but acts as a chromatic or altered chord in the other.

For example, consider a modulation from C major to E♭ major. These keys share no diatonic triads. However, if we borrow the F minor chord (iv) from the parallel key of C minor (a technique we explored in Chapter 3.4 (Modal Mixture)), we can use it as a pivot. In the old key of C major, F minor is a borrowed modal mixture chord. But in the new key of E♭ major, F minor is the perfectly diatonic supertonic (ii) chord.

By playing C major → F minor → B♭7 → E♭ major, we have successfully used a chromatic pivot (F minor) to smoothly transition to a remote key. The chromatic alteration leads one or more voices by a half-step, creating a seamless and logical pathway into the new tonal territory.

4.5.4Enharmonic Modulation and the Diminished 7th

To achieve truly magical and unexpected modulations, composers turn to enharmonic modulation. This technique relies on the fact that certain chords can be spelled differently (enharmonically) to change their harmonic function entirely.

The most powerful tool for enharmonic modulation is the fully diminished 7th chord (first introduced in Chapter 3.2 (Diminished 7th Chords)). Because the fully diminished 7th chord is built entirely of stacked minor third intervals, it is perfectly symmetrical. It technically has no single root note. As a result, any fully diminished 7th chord can be respelled to function as the leading-tone chord (vii°7) in four completely different keys.

Consider the diminished 7th chord B–D–F–A♭ (the vii°7 in C minor). If we simply respell the A♭ as a G♯, the chord becomes G♯–B–D–F. This is now the vii°7 chord in the key of A minor. By sounding the chord in the context of C minor, but resolving it as if it were in A minor, the composer can instantly transport the listener to a key located a minor third away.

Because there are only three unique fully diminished 7th chords in the 12-tone system (before they begin inverting into themselves), this single chord type acts as a master key, capable of unlocking pathways to almost any remote tonal centre.

Another common enharmonic pivot is the German Augmented 6th chord (which we explored in detail in Chapter 4.3 (Augmented Sixth Chords and Tritone Substitution)). A German 6th chord sounds exactly identical to a dominant 7th chord. For example, a C dominant 7th chord (C–E–G–B♭) sounds exactly the same as a German 6th built on C (C–E–G–A♯). A composer can approach the chord as a standard dominant 7th, but resolve it as an augmented 6th (moving outward to the dominant of the new key), executing a startling and sophisticated modulation.

4.5.5Sequential Modulation

Finally, we can reach remote keys through sequential modulation. In this technique, a melodic phrase or a specific harmonic progression is repeated at a different pitch level. The sheer momentum of the repetition carries the music into the new key.

In a sequential modulation, traditional harmonic function becomes secondary to the logic of the sequence itself. The ear accepts the new key not because it was prepared with a traditional dominant-to-tonic cadence, but because the pattern of the sequence dictates the destination.

For example, a composer might write a progression that moves down a whole step: C major → B♭ major → A♭ major. The sequence itself is the modulatory vehicle. This technique is highly effective for moving quickly through several transient key centres before finally settling on a remote destination.

Sequential modulation drives the roving, exploratory harmony found in many jazz compositions - for instance, the sequence of whole-tone descents found in sections of Thelonious Monk's Epistrophy (1942), where a repeating two-chord pattern descends in whole steps, pulling the listener through a series of rapidly shifting tonal centres before the next cadence arrives.