Predominant Seventh Chords - AP Music Theory Study Guide

Getting Started

Having mastered the function of predominant triads like the supertonic (ii) and subdominant (IV), we now explore how adding a seventh to these chords creates richer harmonies. These predominant seventh chords intensify the musical drive towards the dominant, adding a specific dissonance that requires careful handling in voice leading. This chapter focuses on the procedures for correctly writing and analyzing these essential chords.

What You Should Be able to Do

• Provide a Roman numeral and figured bass analysis for predominant seventh chords in major and minor keys.

• Write four-part progressions using predominant seventh chords, demonstrating correct voice leading.

• Identify the chordal seventh in any predominant seventh chord and resolve it correctly.

• Detect and correct voice-leading errors, such as improper seventh resolution or parallel motion, in exercises containing these chords.

• Aurally distinguish the sound of a predominant seventh chord from its triadic counterpart.

Key Concepts & Analysis

The use of predominant seventh chords is governed by principles of voice leading, which ensure melodic smoothness and harmonic clarity. While these chords serve a familiar harmonic function, the addition of a fourth note—the chordal seventh—introduces a dissonance that must be handled with a specific procedure.

The Predominant Seventh Chords

A seventh chord is a four-note chord built from a root, a third, a fifth, and a seventh. A predominant chord is a chord whose harmonic function is to prepare the arrival of the dominant. Therefore, a predominant seventh chord is a seventh chord built on a predominant scale degree, most commonly the supertonic (^2) or the subdominant (^4).

• In major keys, the common predominant seventh chords are the supertonic minor seventh (ii7) and the subdominant major seventh (IV7).

• In minor keys, they are the supertonic half-diminished seventh (iiø7) and the subdominant minor seventh (iv7).

The Cardinal Rule: Resolving the Chordal Seventh

The most important voice-leading principle for any seventh chord in this style is the treatment of the chordal seventh, which is the note an interval of a seventh above the root of the chord. Because it creates dissonance, this note has a strong melodic tendency that must be fulfilled.

Essential Knowledge: The chordal seventh must resolve down by a descending step into a note of the following chord.

This rule is unwavering, regardless of which voice (soprano, alto, tenor, or bass) contains the seventh or which inversion the chord is in. For example, in C major, the chordal seventh of a ii7 chord (C-E-G) is the note C (^1). When the ii7 chord moves to a V chord (G-B-D), the C must resolve down by step to B (^7), which is the third of the V chord.

Example Progression:ii6/5 – V in C major

• The notes of ii6/5 are F-A-C-D (with F in the bass).

• The chordal seventh is C.

• The notes of V are G-B-D.

• The C in the ii6/5 chord must move to B in the V chord.

Voice-Leading Procedures

Applying the resolution rule while adhering to other voice-leading conventions is key.

1. Doubling and Spacing

In a root position seventh chord, all four members (root, third, fifth, seventh) are typically present, so no doubling is necessary. This is the standard practice. Keep upper voices (soprano, alto, tenor) within an octave of each other for proper spacing.

2. Avoiding Parallel Motion

The addition of a fourth voice part increases the risk of creating forbidden parallel motion (two voices moving in the same direction to the same interval, specifically a perfect fifth or perfect octave). Always check the movement between all voice pairings when moving from a predominant seventh to the dominant.

• Common Pitfall: The progression IV7 to V in root position can easily lead to parallel fifths if not handled carefully. To avoid this, one chord is often incomplete, or contrary motion is used. However, progressions like ii6/5 – V or iv7 – V are generally less problematic.

3. Inversions

Predominant seventh chords are frequently used in inversion to create smoother bass lines. The most common are first inversion chords like ii6/5 and iv6/5. The resolution rule for the chordal seventh remains the same regardless of the inversion.

• In a ii6/5 chord, the bass note is the third of the chord (^4). This creates a smooth bass line of ^4–^5 when moving to a root-position V chord.

• In a ii4/3 chord, the bass note is the fifth of the chord (^6).

• In a ii4/2 chord, the bass note is the seventh of the chord (^1). This is less common but creates a bass line of ^1–^7 when moving to a V6 chord.

In all cases, locate the chordal seventh and ensure it moves down by step in the subsequent chord.

Data & Organization Tools

This table outlines the diatonic seventh chords built on the supertonic and subdominant in major and minor keys, which function as predominants.

Evidence Bank

• Predominant Function: The harmonic role of preparing the arrival of the dominant chord. Predominant seventh chords fulfill this role with greater intensity than triads.

• Chordal Seventh: The note located a seventh above the root of any seventh chord. It is the primary source of the chord's dissonance.

• Resolution: The movement of a dissonant note to a consonant one. In this style, resolutions are typically stepwise.

• Descending Stepwise Resolution: The mandatory voice-leading procedure for all chordal sevenths in the common practice style.

• ii7 Chord: The supertonic minor seventh chord in a major key (e.g., D-F-A-C in C major). A very common predominant seventh chord.

• IV7 Chord: The subdominant major seventh chord in a major key (e.g., F-A-C-E in C major). Its chordal seventh is the leading tone.

• iiø7 Chord: The supertonic half-diminished seventh chord in a minor key (e.g., B-D-F-A in a minor).

• iv7 Chord: The subdominant minor seventh chord in a minor key (e.g., D-F-A-C in a minor).

Skill Snapshots

• Functional:

  1. I – ii6/5 – V – I: The ii6/5 intensifies the move to V with the dissonance of its seventh.

  2. i – iv7 – V – i: A standard progression in minor, where the iv7 smoothly connects the tonic and dominant areas.

  3. I – IV – ii4/2 – V6 – I: The ii4/2 provides a strong melodic bass line (^1–^7) leading into an inverted dominant.

• Voice-Leading:

  1. Rule: The chordal seventh must resolve down by step. → Effect: This creates a smooth, predictable melodic line and properly resolves the chord's primary dissonance.

  2. Rule: When writing a root position seventh chord, include all four chord members (root, 3rd, 5th, 7th). → Effect: This avoids doubling issues and presents the chord's full, characteristic sound.

  3. Rule: Check for parallel fifths and octaves between all voices, especially when moving to the dominant. → Effect: This maintains the independence of the melodic lines, a foundational principle of four-part writing.

• Form:

  1. Baseline Phrase: A phrase can be extended by inserting a predominant seventh chord before the dominant, such as I – IV – V – I becoming I – ii7 – V – I.

  2. Cadential Contrast: A half cadence (...ii6/5 – V) feels more powerful than one with a simple triad (...ii – V) because the seventh's resolution pulls the harmony forward.

  3. Continuity: Predominant seventh chords are rarely final chords; their inherent dissonance and function demand continuation to the dominant, making them ideal for use in the middle of a phrase.

Common Misconceptions & Clarifications

• Misconception: The chordal seventh can resolve upwards if it sounds better.

  • Clarification: In the harmonic language of this period, the downward resolution of a chordal seventh is a fundamental rule, not a stylistic choice. Upward motion is incorrect.

• Misconception: A predominant seventh chord is just a "fancier" version of the triad with no new rules.

  • Clarification: While the harmonic function is the same, the addition of the seventh introduces a significant voice-leading obligation—its downward stepwise resolution—that does not exist for the triad.

• Misconception: The chord IV7 in a major key is a dominant chord because it contains the leading tone.

  • Clarification: Although the seventh of the IV7 chord is the leading tone (^7), the chord's root on ^4 and its typical movement to V firmly establish its predominant function. It prepares the dominant; it does not function as one.

• Misconception: You can omit the seventh of the chord if it is difficult to resolve.

  • Clarification: Omitting the seventh turns the chord back into a simple triad. To be a seventh chord, it must contain the seventh, and that seventh must be resolved correctly.

Summary

Predominant seventh chords, such as ii7, IV7, iiø7, and iv7, serve the same harmonic function as their triadic counterparts by preparing the dominant. However, they increase the harmonic tension and drive through the inclusion of a dissonant chordal seventh. The essential procedure for using these chords is rooted in voice leading: the chordal seventh must always resolve down by a single step into a note of the subsequent chord. Mastering this rule, while continuing to avoid parallel motion and maintain proper spacing, allows for the creation of richer and more compelling harmonic progressions. These chords are a vital tool for adding color and momentum to the basic tonal framework.