How does functional harmony create a sense of key, tension and resolution, and how do we label it?
Analyse harmony and tonality using triads and inversions, Roman-numeral and functional labelling, cadences, and the identification of keys and modulations
A focused answer to the H2 Music outcome on harmony. Triads and inversions, Roman-numeral and functional analysis, the four cadence types, the tonic-predominant-dominant cycle, and recognising keys and modulations.
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What this dot point is asking
SEAB wants you to analyse harmony and tonality: to label chords with Roman numerals, describe their function, identify the four cadence types, recognise the key of a passage, and account for modulations to new keys. The central insight is that common-practice harmony is a system of tension and resolution, organised around a tonal centre, and that the analyst's job is to make that system explicit.
The answer
The musical concept: triads, inversions and Roman numerals
A triad is a three-note chord built in thirds: a root, a third and a fifth. In a key, a triad is named by the scale degree of its root using a Roman numeral, upper case for major chords and lower case for minor. In C major: I (C major), ii (D minor), iii (E minor), IV (F major), V (G major), vi (A minor), and the diminished vii.
Chords can be inverted. With the root in the bass the chord is in root position; with the third in the bass it is in first inversion (figured 6); with the fifth in the bass it is in second inversion (figured 6/4). The dominant seventh adds a seventh above the root (V7) and is a strong driver toward the tonic.
The technique: harmonic function and cadences
Harmony is organised by function into three families:
- Tonic (T): I (and vi) - home, repose.
- Predominant (PD): IV and ii - preparation, leaning toward the dominant.
- Dominant (D): V and vii - tension, demanding resolution to the tonic.
The basic cycle is T to PD to D to T. A cadence is the harmonic punctuation at a phrase ending:
- Perfect (authentic): V to I, full closure.
- Imperfect (half): any chord to V, an open, unfinished feel.
- Plagal: IV to I, the "Amen" cadence.
- Interrupted (deceptive): V to vi, the expected tonic withheld for surprise.
Named repertoire: tonality in action
Bach's chorales are the densest school of functional harmony, with a cadence every two or four bars. Mozart's and Haydn's expositions show large-scale tonality: a movement in a major key moves to the dominant; a minor-key movement moves to the relative major.
Examples in context
Example 1. J.S. Bach, chorale harmonisations. Each phrase ends in a clearly defined cadence, and the inner voices move by smooth functional progressions. They are the standard model for studying root-position and inverted triads, the dominant seventh, and cadence types at close range.
Example 2. Mozart, Piano Sonata in C major K. 545, first movement. The exposition establishes C major then modulates to the dominant, G major, confirmed by a perfect cadence, before the development explores related keys. It is a clear illustration of large-scale tonality and modulation within sonata form.
Try this
Q1. Label the chords of a perfect cadence and a plagal cadence using Roman numerals. [2 marks]
- Cue. Perfect cadence: V to I. Plagal cadence: IV to I.
Q2. Explain the difference between a chord in first inversion and one in second inversion. [2 marks]
- Cue. First inversion (figured 6) has the third of the chord in the bass; second inversion (figured 6/4) has the fifth in the bass.
Q3. Describe how a composer modulates from a major key to its dominant. [3 marks]
- Cue. Introduce the leading note of the new key via an accidental (raising the fourth degree of the old key), often through a pivot chord common to both keys, then confirm the new key with a perfect cadence in it.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original8 marksA short passage in C major moves through the following chords on successive beats: C major, F major, G major, C major, then a bar later F major, G major, A minor. Label each chord with a Roman numeral, identify the two cadences, and explain the harmonic function of each chord in the first progression.Show worked answer →
Label the chords. In C major: C major = I, F major = IV, G major = V, C major = I; then F major = IV, G major = V, A minor = vi.
Identify the cadences. The first progression ends V to I, a perfect (authentic) cadence, giving full closure. The second ends V to vi, an interrupted (deceptive) cadence, where the expected I is replaced by vi, creating surprise and delaying resolution.
Explain the function. I is tonic (home, stable); IV is predominant (subdominant function, preparing the dominant); V is dominant (tension demanding resolution to I). The cycle tonic to predominant to dominant to tonic is the engine of common-practice harmony.
Markers reward correct Roman numerals, the two cadence labels, and the functional account (tonic, predominant, dominant). A strong answer notes that the interrupted cadence prolongs the phrase by avoiding closure.
Original10 marksExplain how a composer establishes a new key (modulation) within a movement. Refer to the role of the pivot chord, accidentals, and a confirming cadence, with reference to music you have studied.Show worked answer →
Define the goal. Modulation is the process of changing the tonal centre so a new key is heard as home, not merely as a passing chord.
Account for the mechanism. A common-practice modulation often uses a pivot chord that belongs to both the old and new keys, smoothing the join. New accidentals then appear, especially the leading note of the new key (the raised seventh). The new key is confirmed by a perfect cadence in that key. The most frequent move is from tonic to dominant (for example C major to G major), achieved by introducing F sharp, the leading note of G.
Evaluate. Markers reward the pivot-chord concept, the appearance of the new leading note via accidentals, and the confirming cadence, plus a real example (a Classical exposition modulating to the dominant, or a minor-key movement moving to the relative major). The strongest answers distinguish a true modulation from a brief tonicisation.
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