Progression from V7 to ♭VI: An Integrated Analysis of Harmonic Connection, Borrowed Chords, and the Aesthetics of Modulation
1. Introduction: Deconstructing the Query and Establishing the Theme
We will conduct a multifaceted analysis, focusing on the perspective of chromatic mediants, to address the harmonic question of why a V7 chord (G7) in Key C can smoothly progress to a ♭VI chord (A♭) whose root is a semitone higher.
According to strict harmonic theory, chords in a chromatic mediant relationship are defined as having roots separated by a major or minor third and sharing at least one common tone. However, comparing the G7 (G-B-D-F) and A♭ (A♭-C-E♭) chords reveals a contradiction in this definition. The roots of both chords, G and A♭, are separated by only a major second (one semitone), and there are no common tones. Therefore, this progression cannot be called a chromatic mediant in the strict sense regarding the relationship between the chords themselves.
However, this progression is musically persuasive because its aesthetic effect shares deep commonalities with the aesthetics of "color" and "surprise" brought about by chromatic mediants. To resolve this contradiction, we will clarify the two main mechanisms that make this progression successful.
1) Voice-leading techniques where each voice connects smoothly with minimal movement. 2) A harmonic approach of adding altered tones to the dominant chord.
We will demonstrate that this progression is not merely a deviation from rules, but rather a compositional technique and harmonic thought process.
2. Theoretical Foundations: Definitions of V7 and Chromatic Mediants
2.1. Traditional Function of the V7 Chord (G7)
The G7 chord (G-B-D-F), which is the V7 chord in Key C, is the chord containing the most powerful tension in classical functional harmony. This tension is created by the two guide tones that compose the chord: the major third B (the leading tone of Key C) and the minor seventh F 3. These tones create a strong gravitational pull toward the tonic C major (I) chord by resolving a semitone upward (B→C) and a semitone downward (F→E), respectively 4. This progression from V7 to I is known as a perfect authentic cadence and is the most fundamental harmonic framework for establishing the conclusion or stability of a musical piece.
2.2. Definition of Chromatic Mediants
Chromatic mediants are a technique that uses chords whose roots are in a third relationship, which are not found among the diatonic chords of a scale. Although there are differences of opinion among music theorists regarding their definition, they are generally classified into the following two models.
Conservative definition: A relationship where the roots of two chords are separated by a major or minor third, the chord quality (major or minor) is the same, and they share one common tone. For example, the major chromatic mediants for a C major chord (C-E-G) are E major (E-G#-B) and A♭ major (A♭-C-E♭). The former shares the common tones E and G, while the latter shares the common tone C. A♭ major shares the common tone C with the C major chord, fitting this definition.
Broad definition (double chromatic mediant): A relationship where the roots are separated by a third, but they share no common tones and the chord qualities differ. Examples include the C major chord and the E♭ minor chord (E♭-G♭-B♭) or A♭ minor chord (A♭-C♭-E♭) 1.
3. Mechanisms of Progression: Primary Analytical Models
Although the progression from G7 to A♭ is not a chromatic mediant relationship in the strict sense, its harmonic effect shares the aesthetics of chromatic mediants. The persuasiveness of this progression is explained primarily by the following two harmonic mechanisms.
3.1. Voice Leading: Connection through Minimal Movement
In harmony, transitions between chords are smoothed by "voice leading," where each voice moves smoothly to the nearest note. Analyzing the progression from G7 (G-B-D-F) to A♭ (A♭-C-E♭) voice by voice will reveal how this progression is composed of efficient and aurally pleasing movements.
Bass (root of G7): G moves up a semitone to become A♭. This is the root of the A♭ chord, an extremely smooth movement where the harmonic foundation shifts by a semitone.
Third (major third of G7): B moves up a semitone to become C. This is a natural resolution to C as the leading tone of Key C, and it takes on a new role as the third of the A♭ chord.
Seventh (minor seventh of G7): F moves down a whole tone to become E♭. This is the fifth of the A♭ chord, and the interval is connected by the minimal movement of a whole tone.
5th degree (5th of G7): D descends a whole step to C, or descends a half step to D♭ (the displacement of A♭ from the major 3rd to the minor 3rd) 3. This voice is also led to the next chord with minimal movement.
This smoothness of voice leading allows for a harmonically pleasing transition while defying traditional expectations of resolution.
3.2. V7 as a displaced chord: Utilizing hidden common tones
In more sophisticated harmony (especially in jazz and Romantic music), it is common for tension notes or displaced tones to be added to dominant chords. Analyzing G7 from this perspective, the G7 chord is often played as G7♭9. The constituent notes of G7♭9 are G-B-D-F-A♭, and since this chord already contains the A♭ note, the progression from G7 to A♭ can be viewed as a resolution from G7♭9, which has A♭ as a common tone, to an A♭ major chord rooted on that A♭.
Furthermore, this G7♭9 chord can be interpreted as a polychord, G7|B°7, where a B diminished 7th chord (B-D-F-A♭) is superimposed over a dominant G7 chord. Because diminished 7th chords have a symmetry of stacking notes every minor third (B-D-F-A♭-B), they are extremely unstable and have a wide variety of resolutions. This unstable B°7 chord functions as a powerful harmonic bridge that anticipates a resolution to an A♭ major chord rooted on its constituent note, A♭. Thus, while this progression appears to be an abrupt juxtaposition of chords, it is actually based on a clever design grounded in harmonic common tones.
4. Broader context and musical application
4.1. Role as non-functional harmony
The progression from G7 to ♭VI (A♭) is a type of "deceptive cadence" that intentionally avoids the traditional resolution from V7 to I. However, this goes beyond mere harmonic deviation. By defying the listener's expectations, this progression brings about a sudden emotional and colorful change. The harmonic atmosphere shifts in an instant from the bright sound of G major to the darker, more introspective sound of A♭ major. This technique became very frequently used in music after the Romantic period, where harmony became an important element for expressing stories and emotions. It functions as a powerful tool for giving the listener a sense of surprise, mystery, or dreaminess that cannot be depicted by traditional functional harmony alone.
4.2. Modulation and tonal expansion
This progression is not just a connection of chords, but can also play a role within a larger tonal structure. It is extremely important that A♭ is ♭VI in Key C, while simultaneously being the IV chord of Key E♭. This suggests that the progression from G7 to A♭ can be interpreted as a direct modulation from Key C to Key E♭. In this case, G7 no longer functions as the dominant of Key C, but as a chord preparing for the transition to the next tonality. The A♭ chord takes on the role of inducing a progression to the next V (B♭) or I (E♭) as the subdominant of Key E♭, establishing a new tonality.
4.3. Applications in real examples
This V7-♭VI progression, or similar non-traditional harmonic connections, can be seen in songs across various genres.
John Williams' "Hedwig's Theme": John Williams' works create a mysterious and magical atmosphere by boldly deviating from harmonic norms. Within the tonality of E minor, he intentionally uses non-functional harmony (for example, a series of non-diatonic chords following E minor) to invite the listener into another world 21. This is consistent with the aesthetics of the V7-♭VI progression, which prioritizes the creation of color and atmosphere over harmonic logic.
Queen's "Bohemian Rhapsody": This song is a treasure trove of surprising modulations and chord juxtapositions. Freddie Mercury frequently uses progressions that ignore existing harmonic rules, such as intentionally placing chords in a tritone relationship, like A♭ and D major, next to each other. These bold harmonic choices give the song a dramatic and theatrical character. The G7-A♭ progression is perfectly synchronized with the spirit of "creating drama through non-traditional harmony" that this song embodies.
5. Conclusion: Integration of insights and the evolution of harmony
We have clarified that the progression from G7 to A♭ does not fit the strict definition of a chromatic mediant. However, this progression has shown that its effectiveness is based on other harmonic principles. Specifically, it is the mechanism where smooth voice leading, in which the main voices are connected by minimal movements such as half steps or whole steps, and the V7 chord with a displaced tone (♭9th) resolve the apparent abruptness through a common tone, A♭. The harmonic surprise brought about by this progression is further reinforced by the tonally intuitive relationship that A♭ is the chromatic mediant (♭VI) of Key C.
This V7-♭VI progression is a perfect example of how music theory does not merely describe existing rules, but tells the story of how harmonic language has evolved and expanded its expressive power. Composers have dared to defy the strong functional attraction of dominant-tonic, using non-functional harmony to create color, emotion, and narrative. This progression is typical of the creative techniques that composers since the Classical period have discovered and refined while boldly expanding the framework of harmony, and it continues to demonstrate its power in a wide variety of genres today, including film music, jazz, and pop.