Getting Started
Understanding individual chords and their functions is the foundation of harmonic analysis. Harmonic sequences build upon this knowledge, introducing a powerful, pattern-based logic that composers use to create momentum, extend phrases, and connect different parts of a musical idea. Learning to recognize these patterns is a crucial step toward analyzing longer and more complex musical passages.
What You Should Be Able to Do
Identify the beginning and end of a harmonic sequence in a notated score.
Describe a sequence by its pattern of root movement and its interval of transposition.
Provide a complete Roman numeral analysis for a passage containing a harmonic sequence.
Aurally recognize the presence of common sequential patterns in performed music.
Write a short, harmonically logical passage that employs a diatonic sequence.
Key Concepts & Analysis
The primary lens for understanding harmonic sequences is Functional Harmony. While the internal, chord-to-chord progressions within a sequence often defy the standard Tonic-Predominant-Dominant-Tonic grammar, the sequence as a whole almost always serves a clear, large-scale function. It can prolong a single functional area or create a logical bridge from one function to another.
Definitions
A harmonic sequence occurs when a short progression of chords, called a segment, is immediately repeated one or more times, each time transposed to a new pitch level. The interval of transposition—the distance the segment is moved up or down—is typically kept constant. This harmonic pattern is often, but not always, accompanied by a corresponding melodic sequence, where a melodic figure is similarly transposed.
The most important feature of common-practice sequences is that they are usually diatonic. This means that all the chords in the sequence are derived from the prevailing key. As a result, the quality of the chords (major, minor, diminished) will change from one part of the segment to the next to conform to the key signature. For example, a major chord in the initial segment might become a minor chord when transposed.
Sequences and Harmonic Function
Think of a sequence as a "packaged" harmonic unit. While individual connections inside the package might seem unusual (e.g., IV moving to vii°), the entire package serves a purpose within the larger T → PD → D → T framework.
Prolonging a Function: A sequence can be used to expand a single harmonic function. For instance, a sequence might begin and end on tonic-functioning chords (e.g., I and vi), effectively stretching out the tonic area before the music moves on.
Connecting Functions: More often, a sequence serves as a transition. A common strategy is to use a sequence to connect the Tonic area to the Dominant area, acting as a large, directed predominant gesture that builds energy toward a cadence.
Common Sequential Progressions
The identity of a sequence is defined by the pattern of root movement between its chords.
Descending Fifths (Circle of Fifths): This is the most common and powerful harmonic sequence. The root of each chord is a fifth below (or a fourth above) the previous one. A full diatonic cycle in major would be: I – IV – vii° – iii – vi – ii – V – I. Shorter segments of this pattern are extremely frequent.
- Example in C major:
C – F – B° – e – a – d – G – C
- Example in C major:
Descending Thirds: In this pattern, the roots descend by a step, but the chords often alternate between root position and first inversion to create a smooth descending bassline. The underlying root movement is by thirds.
- Example in C major:
I – V6 – vi – iii6(Roots: C–G–A–E. The C–A and G–E are descending thirds).
- Example in C major:
Ascending Fifths: This sequence involves roots moving up by a fifth (or down by a fourth). It is less common than the descending fifths pattern and tends to create a feeling of lift and energy.
- Example in C major:
I – V – ii – vi – iii
- Example in C major:
In analysis, you must identify the initial segment and then observe how it is transposed. For example, in the progression I – V – ii – vi, the segment is I – V. This segment is then transposed down a step to become ii – vi. This is an ascending fifths sequence transposed down by a second.
Data & Organization Tools
A harmonic function map helps visualize how sequences fit into standard progressions. A sequence often creates a temporary, self-contained loop that ultimately connects two points on the main path.
Harmonic Function Map
Tonic (T): Represents stability and rest.
- Chords: I, vi
Predominant (PD): Creates motion away from tonic, preparing the dominant.
- Chords: IV, ii
Dominant (D): Creates tension that demands resolution to tonic.
- Chords: V, vii°
Standard Path: T → PD → D → T
Sequential Path Example (Circle of Fifths):
T ( I ) → [ IV – vii° – iii – vi – ii ] → D ( V ) → T ( I )
In this example, the bracketed sequence acts as a single, extended predominant function, connecting the initial tonic chord to the structural dominant that precedes the final cadence.
Evidence Bank
Harmonic Sequence: The core concept: a chord progression repeated at a new pitch level. It is used to create structure and forward motion.
Melodic Sequence: A repeated melodic pattern that often accompanies a harmonic sequence, reinforcing the pattern for the listener.
Segment: The initial pattern of chords (typically 2-4 chords) that serves as the model for the sequence.
Transposition: The action of moving the segment to a new pitch level. The interval of transposition is usually constant.
Diatonic Sequence: A sequence in which all chords belong to the established key. This requires chord qualities (major/minor) to change to fit the scale.
Circle-of-Fifths Sequence: The most common sequence, featuring roots that descend by a fifth (e.g.,
vi–ii–V–I). It strongly directs motion toward a goal.Root Movement Pattern: The defining characteristic of a sequence, described by the intervals between the roots of its chords (e.g., descending fifths, descending thirds).
Skill Snapshots
Functional
Progression:
I – IV – vii° – iii- Why it's valid: This is a segment of the circle-of-fifths sequence. It prolongs the tonic area by moving from I to its relative minor substitute, iii.
Progression:
I – V6/5 – vi – IV4/3- Why it's valid: This sequence, with its descending stepwise bassline, connects the tonic (I) to the predominant (IV), setting up a move to the dominant.
Progression:
ii – V – I- Why it's valid: While a simple cadential formula, it can also be the final part of a longer circle-of-fifths sequence, representing the PD → D → T conclusion.
Voice-Leading
Rule: The strict repetition of the pattern takes priority over some standard voice-leading rules. Effect: A leading tone (^7) appearing in the middle of a sequence may not resolve to the tonic (^1) if the pattern dictates it move elsewhere.
Rule: Chordal sevenths within a sequence almost always resolve down by step. Effect: This creates smooth, connected lines between chords, even when the root movement is in larger leaps.
Rule: To remain diatonic, the interval quality must adapt to the scale. Effect: A perfect fifth between two voices in the first segment may become a diminished fifth in a later transposition to avoid using non-key notes.
Form
Baseline Phrase: A simple phrase often moves directly from tonic to a cadence (e.g.,
I – IV – V – I).Phrase with Sequence: A sequence can extend the middle of a phrase, delaying the cadence and building momentum (e.g.,
I – [vi – ii – V] – I, where the bracketed part is a sequential fragment).Continuity: The repetition inherent in a sequence provides strong musical coherence, making a passage feel unified and logical.
Common Misconceptions & Clarifications
Misconception: Any repeated musical idea is a sequence.
- Clarification: A harmonic sequence specifically requires the transposition of a progression of chords. A repeated bass note or a repeated melodic motive alone does not constitute a harmonic sequence.
Misconception: The chords in a sequence must all be of the same quality (e.g., all major).
- Clarification: In a diatonic sequence, chord qualities must change to fit the key signature. This is a normal and expected feature.
Misconception: Every chord-to-chord motion within a sequence must follow standard functional rules.
- Clarification: The internal logic of the sequence's pattern temporarily overrides the standard T-PD-D-T grammar. The function of the sequence should be evaluated as a whole unit.
Misconception: A sequence is a type of cadence.
- Clarification: A sequence is a technique used to elaborate the material within a phrase. A cadence is a specific formula of two or more chords that concludes a phrase. A sequence often leads to a cadence.
Summary
A harmonic sequence is a fundamental compositional tool where a segment of chords is systematically transposed, creating a predictable and propulsive musical structure. These patterns are typically diatonic, meaning the quality of the chords adapts to fit the established key. While the chord-to-chord connections within a sequence may not adhere to standard functional progressions, the sequence as a whole serves a clear purpose: either to prolong a single harmonic area or to create a seamless transition between different harmonic functions, most often from tonic to dominant. Recognizing the segment, the interval of transposition, and the overall function of the sequence is essential for both written and aural analysis.