4.3 Harmonic Progression, Functional Harmony, and Cadences

Harmonic progression is the ordered sequence of chords under a passage, and in tonal music every chord acts as tonic (T), dominant (D), or predominant (PD). Cadences are the resting points that end phrases, with the perfect authentic cadence (PAC) being the strongest.

Why This Matters for the AP Music Theory Exam

This topic trains you to think about chords as connected pieces of a system, not random stacks. That thinking shows up across the AP Music Theory exam:

• In score analysis and harmonic listening, you label chords with Roman numerals and explain whether each one functions as tonic, dominant, or predominant.
• In outer-voice dictation, recognizing tonic-dominant-tonic motion helps you predict the bass line and check your work.
• When you identify cadences, you locate phrase endings, which connects to phrase and form questions later in the course.
• When you build or realize progressions, knowing normative chord successions keeps your harmony in the common-practice style.

You do not need to memorize the physics of overtones or full music history. You do need to recognize function and cadence type quickly, both by ear and from notation.

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Key Takeaways

• Tonal music organizes all pitches around a central tonic, the system used in Western common-practice music from about 1650 to 1900.
• Every chord in a progression has a function: tonic (T), dominant (D), or predominant (PD).
• Tonic-dominant-tonic is the most fundamental progression for establishing a key.
• Harmonic rhythm is how fast chords change; faster harmonic rhythm can make a passage feel like it is moving more, even at the same tempo.
• Cadences split into conclusive (perfect authentic, plagal) and inconclusive (half, imperfect authentic, deceptive).
• A PAC is V-I with both chords in root position and scale degree 1 in the soprano; any other V-I that breaks one of those conditions is an IAC.

Tonal Music and Function

Music is tonal when all the pitch content is organized around a central pitch called the tonic, with every other pitch relating to it in a fixed, hierarchical way. This is the system that ran through Western common-practice music from roughly 1650 to 1900, and you will also hear tonal organization in popular music, folk music, and jazz.

The tonic is the focal point and usual goal of the music. Every other diatonic chord helps the music move toward or away from that tonic. The tonic triad is labeled with the Roman numeral I (or i in minor).

In tonal music, chord order is governed by a web of relationships, and each chord has a contextual role called its function. Every chord in a progression can be described as one of three functions:

• Tonic (T): the point of rest and resolution (I/i).
• Dominant (D): strong pull back toward tonic, usually right before it.
• Predominant (PD): sets up the dominant.

Dominant Function

Dominant chords usually come right before the tonic, and moving from dominant to tonic creates a feeling of resolution. The V chord and the vii° chord both carry dominant function. Even in a minor key, the dominant-functioning versions are V and vii°, not v or VII.

Look at why these pull so strongly toward tonic. In the key of B♭ major:

The V chord contains scale degrees 5, 7, and 2, and the vii° chord contains scale degrees 7, 2, and 4. Scale degrees 7 and 2 both resolve to tonic (scale degree 1) by step, so they act as tendency tones. Scale degree 7 is the leading tone, which gives it an especially strong pull upward to tonic.

The V chord is the stronger dominant of the two. It contains scale degree 5, which pulls toward scale degree 1, and it shares its root with the fifth of the tonic chord, so V to I voice leading tends to be smooth.

Predominant Function

Predominant chords usually appear before dominant chords and prepare them. Several chords can fill this role, and you will study them in more detail in 5.1 Adding Predominant Function IV (iv) and ii (ii0) to a Melodic Phrase. For now, know that IV (iv) and ii (ii°) commonly act as predominant chords.

Harmonic Progression and Harmonic Rhythm

A harmonic progression (or chord progression) is the specific sequence of chords under a passage. You write it as a string of Roman numerals, adding Arabic numerals for inversions, just like the figured-bass work from Unit 3.

Harmonic rhythm is the rate at which chords change. A phrase in 4/4 might begin with one chord per measure and then shift to chords changing every half note or quarter note, which is an acceleration of harmonic rhythm. Even if the tempo stays the same, faster chord changes make a passage feel like it is moving more quickly.

The most fundamental progression for establishing a key is tonic-dominant-tonic (I-V-I in major, i-V-i in minor). Most tonal progressions are some expansion of tonic-predominant-dominant-tonic.

Common-practice style favors certain chord successions and avoids others. Moving in the "wrong" direction, such as V to IV, is called a retrogression. V to IV is common in some popular styles but is generally avoided in common-practice writing.

Cadences

A cadence is the point of relative repose that ends a harmonic progression or phrase. Cadences act like punctuation, marking where phrases end and shaping musical form. They fall into two groups:

• Conclusive: perfect authentic and plagal cadences.
• Inconclusive: half, imperfect authentic, and deceptive cadences.

Inconclusive cadences are usually followed by more music. Conclusive cadences tend to close off a phrase, section, or whole piece.

Half Cadence

A half cadence ends a phrase on a V chord. Because V has dominant function, a half cadence sounds unresolved, like a musical question waiting for an answer.

Deceptive Cadence

A deceptive cadence sets up a V chord that sounds like it should resolve to tonic, but instead moves to a non-tonic chord, often vi (VI). The "surprise" resolution is what makes it deceptive.

Plagal Cadence

A plagal cadence moves from IV (iv) to the tonic. It is sometimes called the "amen" cadence because of its use in hymns. Even without a dominant chord, the plagal cadence counts as a conclusive resolution.

Authentic Cadences: PAC and IAC

The authentic cadence is a V-I (or dominant-to-tonic) motion and comes in two forms.

• Perfect authentic cadence (PAC): V-I with both chords in root position and scale degree 1 in the soprano. This is the strongest, most final cadence.
• Imperfect authentic cadence (IAC): still a V-I progression, but at least one of the PAC conditions is broken. That means one or both chords are inverted, and/or the soprano ends on a chord tone other than scale degree 1.

Imperfect authentic cadence (IAC):

Perfect authentic cadence (PAC):

A leading-tone chord (vii°) can stand in for dominant function at these cadences, but keep your PAC and IAC definitions centered on the root-position requirement and the soprano scale degree. A textbook PAC is specifically a root-position V-I.

Picardy Third

Some progressions are distinctive enough to earn a special label. The Picardy third is a major tonic chord ending a section that is in a minor key. Watch for the raised third that makes the final tonic major instead of minor.

How to Use This on the AP Music Theory Exam

Score Analysis

• Label each chord with a Roman numeral, then tag it T, D, or PD so you can see the shape of the progression.
• Check the final chord of each phrase for cadence type. Look at the last two chords, whether they are in root position or inverted, and what scale degree is in the soprano.
• Watch for retrogressions like V to IV, which signal either a stylistic choice outside common practice or a possible error to flag.

Listening and Dictation

• Train your ear to hear tonic-dominant-tonic motion. Hearing where the dominant pulls back to tonic helps you predict the bass line in outer-voice dictation.
• Listen for the feeling of arrival. A strong, settled ending with the melody landing on tonic usually signals a PAC; an "unfinished question" ending usually signals a half cadence.
• Track harmonic rhythm. Noticing when chords start changing faster helps you place chords accurately in time.

Common Trap

• Do not assume any V-I is a PAC. Confirm root position in both chords and scale degree 1 in the soprano before you call it perfect.
• Do not confuse a deceptive cadence (V to a non-tonic chord, often vi) with a half cadence (phrase actually ends on V).

Common Misconceptions

• "Dominant function means the v chord." In minor keys, the dominant-functioning chords are V and vii°, with a raised leading tone, not v or VII.
• "Any V-I is a perfect authentic cadence." A PAC requires both chords in root position and scale degree 1 in the soprano. Break either condition and it becomes an IAC.
• "Plagal cadences are weak because they have no dominant." The plagal cadence (IV-I) is still classified as a conclusive cadence.
• "A deceptive cadence is the same as a half cadence." A half cadence ends on V; a deceptive cadence reaches V and then resolves to a non-tonic chord, often vi.
• "vii° is just a weaker tonic chord." The vii° chord carries dominant function and pulls toward tonic, because it contains the leading tone and other tendency tones.
• "Faster music means faster harmonic rhythm." Harmonic rhythm is about how often chords change, not tempo. Chords can change quickly at a slow tempo or slowly at a fast tempo.

Quick Check

In Roman numerals, what are the basic tonic-dominant-tonic progressions in both major and minor? Try writing them out: I-V-I for major and i-V-i for minor. Remember that the dominant uses a raised leading tone in minor, so it stays V rather than v.

Related AP Music Theory Guides

• 4.1 Harmony and Voice Leading I
• 4.2 SATB Voice Leading
• 4.5 Voice Leading with Seventh Chords in Inversions
• 4.4 Voice Leading with Seventh Chords
• Unit 4 Overview: Harmony and Voice Leading I (Chord Function, Cadence, and Phrase)