The vi (VI) Chord - AP Music Theory Study Guide

Getting Started

Having mastered the foundational harmonic functions of tonic, predominant, and dominant, we now expand our harmonic vocabulary. The submediant chord introduces a new layer of color and complexity, capable of acting in two distinct functional roles and creating one of music's most powerful moments of surprise.

What You Should Be able to Do

• Identify the submediant chord (vi or VI) by sight and sound in major and minor keys.

• Provide a correct Roman numeral analysis for progressions that include the submediant chord.

• Describe the harmonic function of a vi (or VI) chord as either a tonic substitute or a predominant.

• Aurally and visually identify a deceptive progression and the deceptive cadence it often creates.

• Differentiate between the quality of the submediant chord in major (minor vi) and minor (major VI) keys.

Key Concepts & Analysis

The Submediant Chord: A Dual Identity

The submediant chord is the triad built on the sixth scale degree (^6). In a major key, this chord is minor and labeled vi. In a minor key, this chord is major and labeled VI. For example, in C major, the vi chord is A minor (a-c-e). In c minor, the VI chord is A-flat major (Ab-c-eb).

The submediant's primary importance comes from its ability to serve two different harmonic functions, depending on its context within a harmonic progression.

Function 1: Tonic Substitute

Harmonic Function refers to the role a chord plays within the syntax of tonal music, typically categorized as tonic (stability), dominant (tension), or predominant (preparation for the dominant). A Tonic Substitute is a chord that shares pitches with the tonic (I) chord and can be used to extend or prolong the tonic area without providing the finality of the tonic itself.

The vi chord is the most common tonic substitute. It shares two crucial pitches with the I chord: scale degrees ^1 and ^3. Because of this overlap, the vi chord can follow the tonic chord smoothly, creating a sense of gentle departure while remaining firmly within the tonic area of the harmonic map.

• Common Progression:I – vi

• Analysis: This motion prolongs the tonic function. Instead of simply repeating I, the progression moves to vi, offering fresh harmony while retaining the stable character of the tonic area. From vi, the progression will typically move toward the predominant area.

Function 2: Weaker Predominant

A Predominant Function chord serves to prepare the arrival of the dominant. The strongest predominant chords are IV and ii, as they lead smoothly to V. The vi chord can also serve a predominant function, but it is considered weaker than IV or ii. It does not create as strong a pull toward the dominant.

The vi chord often acts as a bridge between the tonic area and a stronger predominant chord. This creates a longer, more developed harmonic phrase.

• Common Progression:I – vi – IV – V – I

• Analysis: Here, vi follows the tonic. Instead of returning to tonic, it progresses to IV, a stronger predominant. In this context, vi functions as the first step away from tonic stability and toward the tension of the dominant.

The Deceptive Progression: Subverting Expectation

The most dramatic and distinctive use of the submediant chord occurs in the deceptive progression. This is a specific harmonic progression where the dominant chord (V) resolves not to the expected tonic (I), but to the submediant (vi or VI).

• The Progression:V – vi (in major) or V – VI (in minor)

• Analysis: The dominant chord creates a powerful expectation of resolution to the tonic. By moving to the submediant instead, the progression sidesteps this expectation, creating harmonic surprise. The listener is "deceived" into thinking the phrase will end, but it is instead extended.

When a deceptive progression occurs at the end of a phrase, it creates a deceptive cadence. This cadence is a powerful tool for composers to delay closure, extend musical ideas, and build suspense before an eventual, stronger cadence.

Data & Organization Tools

This table shows the diatonic triads in a major key and their common functions. Note the dual role of the vi chord.

Diatonic Triads and Functions in C Major

Evidence Bank

• Submediant Chord: The triad built on the sixth scale degree (^6) of the key. It is minor (vi) in major keys and major (VI) in minor keys.

• Harmonic Function: The role a chord plays in a progression, categorized as tonic (rest), predominant (preparation), or dominant (tension).

• Tonic Substitute: A chord, most often vi, that can replace or prolong the tonic chord due to sharing common tones. It is used to extend the tonic area.

• Predominant Function: The role of a chord that prepares for the arrival of the dominant. The vi chord can serve as a weaker predominant, often moving to ii or IV.

• Deceptive Progression: The specific harmonic motion of V – vi (or V – VI). Its purpose is to avoid the expected resolution to the tonic.

• Deceptive Cadence: A cadence that ends on a deceptive progression (V – vi or V – VI), creating an effect of surprise and delaying closure.

Skill Snapshots

• Functional:

  1. I – vi – ii – V – I: The vi chord functions as a weak predominant, connecting the tonic area to the stronger predominant ii chord.

  2. I – V – vi – IV – V – I: The V – vi motion is a deceptive progression that extends the phrase, which then continues toward a final authentic cadence.

  3. I – IV – V – vi: The vi chord is the surprising goal of a deceptive progression, preventing the phrase from ending after the V chord.

• Voice-Leading:

  1. Rule: In a V – vi deceptive progression, the leading tone (^7) in an outer voice (soprano or bass) should still resolve up to ^1. Effect: This creates a doubled third in the vi chord, which is standard practice for this progression to avoid parallel octaves.

  2. Rule: When moving from I to vi, retain the common tones (^1 and ^3) in the same voices. Effect: This ensures a smooth, stepwise connection between the two chords.

  3. Rule: Avoid moving from V to vi6 (first-inversion submediant). Effect: This motion can easily create parallel fifths and octaves between the bass and upper voices and is generally avoided in common practice.

• Form:

  1. Baseline Phrase: A four-measure phrase ending with a V – I authentic cadence feels complete and closed.

  2. Contrast: A similar phrase that ends with a V – vi deceptive cadence feels incomplete and open, creating an expectation for more music to follow.

  3. Continuity: Composers often use a deceptive cadence at the end of one phrase to elide directly into the beginning of the next, creating a continuous and forward-driving musical narrative.

Common Misconceptions & Clarifications

• Misconception: The vi chord is a strong predominant, just like IV or ii.

  • Clarification: The vi chord is a weaker predominant. It lacks the strong root motion (by fourth or step) to the dominant that characterizes IV and ii. It more often leads to a stronger predominant.

• Misconception: The submediant chord is always minor.

  • Clarification: The submediant is minor (vi) in major keys but is major (VI) in minor keys (e.g., A-flat major in c minor).

• Misconception: Any time a V chord moves to a chord other than I, it is a deceptive progression.

  • Clarification: The term "deceptive progression" specifically refers to the V – vi or V – VI motion. Other progressions, like V – IV6, have different names and functions.

• Misconception: The vi chord and IV chord are interchangeable.

  • Clarification: While both can have a predominant function, they have distinct sounds and typical uses. The vi chord is also a tonic substitute, a role the IV chord does not typically fill.

Summary

The submediant chord (vi in major, VI in minor) is a versatile harmony that significantly enriches the tonal system. It operates with a dual identity, functioning either as a tonic substitute to prolong the opening stability of a phrase or as a weak predominant to initiate movement toward the dominant. Its most notable role is in the deceptive progression (V–vi), where it subverts the listener's expectation for tonic resolution. This progression, often used to form a deceptive cadence, is a key compositional tool for extending phrases, creating surprise, and driving the musical narrative forward. Mastering the functions of the submediant is essential for understanding and analyzing the complexity and expressive depth of tonal music.