Getting Started
Melodic sequence is a fundamental technique composers use to expand and develop a musical idea. Building on the concept of a motive, a sequence takes a short melodic fragment and repeats it at different pitch levels, creating a sense of logical progression and forward motion within a musical phrase. Understanding sequences is key to analyzing how composers create longer, more cohesive musical statements.
What You Should Be Able to Do
Identify a melodic sequence in a notated musical score.
Describe a melodic sequence by its initial melodic segment and its interval of transposition.
Aurally recognize the repeating, transposed pattern of a melodic sequence in performed music.
Analyze the harmonic progression that typically supports a melodic sequence.
Compose a simple melodic sequence based on a given melodic pattern.
Key Concepts & Analysis
Our analysis of melodic sequence will focus on its relationship with functional harmony. While a sequence creates a powerful pattern of its own, this pattern almost always serves a larger harmonic goal, such as prolonging a tonic area or driving the music toward a dominant chord to prepare a cadence.
A melodic sequence occurs when a short melodic idea, or segment, is immediately repeated one or more times at a new pitch level. The process of moving the segment to a new pitch level is called transposition. The interval between the starting pitch of the original segment and the starting pitch of its repetition is the interval of transposition. This interval is typically held constant for the duration of the sequence. For example, if a two-beat segment begins on C and is then repeated beginning on D, it is a sequence up a second.
Functions & The Logic of Sequence
Often, a melodic sequence is supported by a harmonic sequence, where the underlying chord progression is also transposed. This creates a powerful, unified pattern of both melody and harmony.
The internal logic of a harmonic sequence can sometimes appear to override the standard T–PD–D–T functional grammar. For instance, you might see a dominant-function chord move to a tonic-function chord that is not the main tonic of the key (e.g., V resolving to vi). This happens because the integrity of the repeating pattern becomes the primary local rule. However, the entire sequence, taken as a whole, will still serve a clear large-scale function.
Tonic Prolongation: A sequence can be used to expand the tonic area at the beginning of a phrase.
Connecting Functions: A sequence can serve as a bridge connecting the tonic area to the predominant or dominant area.
Driving to the Cadence: A sequence can build momentum leading into a cadential progression.
Common Progressions in Harmonic Sequence
The most common harmonic sequence is the descending fifths sequence, where the root of each chord is a fifth lower than the previous one. In a major key, this pattern often appears as: I – IV – vii° – iii – vi – ii – V – I. Notice how this chain connects all the diatonic chords in the key.
Another common pattern is a descending thirds sequence, such as I – vi – IV – ii. This pattern moves from tonic to predominant function.
Sequences can also ascend. An ascending sequence might involve a pattern like I – V6 – vi – iii6, where the bass line moves up by step while the harmony alternates between root position and first inversion chords.
Diatonic vs. Real Sequence
In most tonal music, sequences are diatonic, meaning the transposed segment is altered to fit within the established key. The generic interval of transposition (e.g., "up a second") remains constant, but the quality of the intervals within the segment may change from major to minor to fit the scale. For example, a segment containing a major third might be transposed to a location in the scale where that interval becomes a minor third. This ensures the music remains in the same key.
Data & Organization Tools
To understand how sequences operate within a key, it is helpful to map the standard functions of diatonic chords. While sequences can create non-standard connections, they ultimately rely on the underlying strength of these functions.
Diatonic Triads & Functions in C Major
| Roman Numeral | Chord | Function |
|---|---|---|
| I | C–E–G | Tonic (T) |
| ii | D–F–A | Predominant (PD) |
| iii | E–G–B | Tonic (T) |
| IV | F–A–C | Predominant (PD) |
| V | G–B–D | Dominant (D) |
| vi | A–C–E | Tonic (T) |
| vii° | B–D–F | Dominant (D) |
Standard Functional Paths: T → PD → D → T. A sequence often creates a chain like T → T → PD → D → T, prolonging one area or efficiently connecting two.
Evidence Bank
Melodic Sequence: The repetition of a melodic segment at a new pitch level. It is a primary tool for melodic development.
Harmonic Sequence: A chord progression that is itself a transposition of a previous progression. It is the typical harmonic support for a melodic sequence.
Segment: The initial melodic or harmonic idea that is to be repeated and transposed. A segment is usually short, from two beats to two measures.
Transposition: The process of moving a segment to a new pitch level, either higher or lower.
Interval of Transposition: The consistent interval by which a segment is moved in a sequence (e.g., up a second, down a third).
Descending Fifths Sequence: The most common harmonic sequence, where roots descend by a fifth (or ascend by a fourth). Example:
vi – ii – V – I.Diatonic Sequence: A sequence where the transposed notes are adjusted to remain within the home key. This is the most common type of sequence in tonal music.
Skill Snapshots
Functional
I – IV – vii° – iii: The beginning of a descending fifths sequence. The pattern of root motion by descending fifth takes precedence over any single chord-to-chord functional rule (likeIVtovii°).I – V6/IV – IV – V6/V – V: A sequence using secondary dominants to tonicize subsequent chords. The pattern is[chord] – [V6 of next chord].I – vi – IV – ii: A descending thirds sequence that effectively moves from a strong tonic (I) to a strong predominant (ii), preparing for the dominant.
Voice-Leading
Rule: Avoid parallel perfect fifths and octaves. Effect: In a diatonic sequence, the changing quality of intervals (e.g., a P5 becomes a d5) naturally helps to break up potential parallelisms between voices.
Rule: Melodic lines should have a clear shape. Effect: The transposition of a melodic segment at a constant interval creates a very clear and predictable contour, making the musical line feel logical and coherent.
Rule: Resolve tendency tones like the leading tone (^7 to ^1). Effect: Within a sequence, this rule may be temporarily suspended. A leading tone might move elsewhere if the sequence's pattern demands it, with the resolution occurring only when the sequence concludes.
Form
Baseline Phrase: A simple four-measure phrase might present a basic idea and move to a cadence (e.g.,
I – IV – V – I).Phrase with Sequence: A sequence can expand this. The same phrase might become
I – V6 – vi – iii6 – IV – V – I, using a two-measure ascending sequence to prolong the tonic area and build momentum before the cadence.Continuity: The repetition inherent in a sequence is a powerful tool for creating continuity. The listener recognizes the pattern and can anticipate its continuation, which pulls the music forward.
Common Misconceptions & Clarifications
Confusing Sequence with Repetition: A sequence requires transposition. Repeating a melodic segment at the exact same pitch level is simple repetition, not a sequence.
Assuming Strict Functional Grammar: The internal chord-to-chord progressions within a harmonic sequence do not always follow the standard T–PD–D progression. The logic of the pattern is the more immediate force.
Expecting Exact Transposition: In tonal music, most sequences are diatonic. Do not be surprised when the quality of an interval changes (e.g., a major third becomes a minor third) to keep the melody within the key signature.
Identifying a Sequence as a Cadence: A sequence is a technique used within a phrase. It leads toward a cadence but is not itself a cadence. The sequence will typically stop to allow for a standard cadential progression (like
ii6/5 – V – I).
Summary
A melodic sequence is a core compositional device where a melodic segment is immediately restated at a new pitch level, typically transposed by a constant interval. This melodic procedure is almost always supported by a corresponding harmonic sequence, creating a unified and propulsive musical pattern. While the internal logic of a sequence can temporarily override standard functional progressions, the sequence as a whole serves a clear purpose, such as prolonging a harmonic area or driving the music toward a cadence. Identifying sequences, both by ear and in the score, is essential for understanding how composers build coherent and developed musical phrases.