Melody sits at an upright piano in a sunlit rehearsal room, one hand resting on the keys mid-phrase, turning toward the learner with a knowing smile as a chord chart taped to the music stand shows Roman numeral analysis of a Bach chorale.
Explain how chords carry tonal functions—tonic, subdominant, and dominant—and describe what each function does within a key.
Identify the Roman numerals I, IV, and V and explain why they are used instead of letter names.
Compare the four main cadence types—authentic, half, plagal, and deceptive—by their harmonic motion and the sense of closure each creates.
Predict whether a phrase will feel complete or suspended based on its final chord pair.
Recognize each cadence type by name when given its chord pair and match it to the rhetorical role it plays in a musical phrase.
Key terms
Tonal function
The structural role a chord plays in a key, such as tonic, subdominant, or dominant.
Leading tone
Scale degree seven, a half step below the tonic, which pulls strongly upward to resolve.
Cadence
A closing chord progression that punctuates a phrase with either closure or suspension.
Perfect authentic cadence
A V to I motion in root position with scale degree one in the melody.
Submediant
The chord built on scale degree six, labeled vi, target of the deceptive cadence.
Where Dominant Tension Comes From
Dominant function is not about a chord being far from the tonic in pitch; it is about voice-leading pull. The dominant carries the leading tone, scale degree seven, which strains upward by a half step into the tonic. When a seventh is added to form V7, a tritone appears between scale degrees seven and four. Scale degree seven resolves up to one and four resolves down to three, so the dissonance unwinds directly into the tonic triad, producing the strongest forward drive in tonal harmony.
Cadences as Punctuation
A cadence frames the end of a phrase the way punctuation ends a sentence. The authentic cadence is a period, providing full closure, strongest when both chords are in root position and the melody lands on the tonic. The half cadence is a comma, ending on the unstable dominant and demanding continuation. The plagal cadence is a gentle affirmation, the Amen tag, and the deceptive cadence is an interrupted thought, dodging the expected tonic by landing on the submediant instead.
Reading a Phrase Rhetorically
Identifying a cadence tells you the rhetorical weight of a phrase. A perfect authentic cadence concludes an argument decisively. A half cadence poses a question and signals more to come. A deceptive cadence delays closure, often to extend a phrase or heighten surprise before the real ending arrives. Composers choose cadence types deliberately to control exactly where a listener feels repose and where they feel pulled forward, shaping the architecture of an entire movement.
Worked examples
Classify the cadence formed by G major to A minor in the key of C major.
Identify each chord by Roman numeral in C major: G major is V, A minor is vi.
The final chord is vi, not the tonic I, so this is not an authentic or plagal cadence.
The motion V to vi is the textbook deceptive cadence pattern.
Note the effect: the leading tone resolves up but the bass moves to the submediant, denying full closure.
Answer: A deceptive cadence (V → vi).
Decide whether D major to G major in G major is a perfect authentic cadence.
Label the chords: D major is V, G major is I in the key of G major.
V to I qualifies as an authentic cadence.
Check the conditions for perfect: both chords must be in root position.
Check that the melody ends on scale degree one, the note G, at the moment of arrival.
If both conditions hold it is perfect; if either fails it is an imperfect authentic cadence.
Answer: Yes, a perfect authentic cadence when both chords are root position and the melody ends on G.
Here is something that will change how you hear every song you know.
In tonal music—the harmonic language of the Western European common-practice tradition (roughly 1600–1900), and its direct descendants in folk, hymn, and popular music—chords are not just colors. They have *jobs*. Theorists call these jobs **tonal functions**.
There are three core functions. **Tonic (T)** is home. The chord built on the first scale degree, Roman numeral **I**, sounds stable and at rest. Your ear treats it as the goal. **Dominant (D)** is the engine of tension. The chord on the fifth scale degree, **V**, carries dominant function through voice-leading convention: its third is scale degree 7 (the leading tone), which pulls strongly upward to tonic. In practice, composers nearly always add a seventh to the dominant, producing **V7**—for example, G–B–D–F in C major. V7 contains a tritone between its third and seventh (scale degrees 7 and 4 of the key). Scale degree 7 pulls upward to 1, and scale degree 4 pulls downward to 3, creating the powerful drive toward I that defines dominant function. **Subdominant (S)** is the departure chord, built on scale degree four, **IV**. It moves away from tonic and prepares the dominant, creating forward momentum without the sharp urgency of V or V7.
The classic motion is T → S → D → T, or I – IV – V – I. You hear this in blues, hymns, pop, and folk music alike.
**Why Roman numerals?** Because function is *relative to the key*. The chord V in C major is G major; in D major it is A major. Roman numerals let you describe the harmonic grammar without rewriting it for every key.
**Cadences** are the punctuation marks of music. A cadence is the chord pair at the end of a phrase that signals closure (like a period) or suspension (like a comma).
- **Authentic cadence (V → I):** The strongest closure. When both chords are in root position and the melody ends on scale degree 1, it is called a *perfect authentic cadence (PAC)*—a full stop. If one chord is inverted or the melody lands elsewhere, it is an *imperfect authentic cadence (IAC)*—a softer landing.
- **Half cadence ( ? → V):** The phrase ends on V, hanging unresolved. It is a musical comma; the listener knows more is coming.
- **Plagal cadence (IV → I):** Gentle and affirming. Associated with "Amen" endings in hymns. The tension is mild because IV does not contain the leading tone.
- **Deceptive cadence (V → vi):** The dominant is expected to resolve to I but instead moves to **vi** (the chord built on scale degree 6, called the submediant). The ear is caught off guard—partially satisfied but not fully settled. Composers use it to extend a phrase or create surprise.
Tension and resolution are not accidents—they are engineered. Composers choose cadence types deliberately to control where the listener feels repose and where they feel pulled forward. When you analyze a piece, the cadence type tells you the phrase's rhetorical weight: does this phrase conclude an argument, or does it ask a question?
**Not sure which cadence type applies?** Start by identifying the very last chord: if it is V, the phrase is open (half cadence); if it is I, check the chord that came just before it—V→I is authentic, IV→I is plagal. If you see V moving somewhere other than I, consider whether vi is the destination (deceptive cadence).
Activity
Drag each chord card to its correct tonal function label, then match each cadence card to its rhetorical role in a musical phrase.
Practice
Given a phrase ending on the dominant chord, name the cadence type and explain its effect.
In D major, identify which cadence the progression G major to D major creates and why.
Common mistakes to avoid
Plagal cadences create more tension than authentic ones.Authentic cadences are stronger because only the dominant contains the leading tone and tritone that drive resolution.
A deceptive cadence ends on the tonic.A deceptive cadence moves from V to vi, the submediant, deliberately avoiding the expected tonic arrival.
Check your understanding
A student claims that a plagal cadence (IV → I) creates stronger tension and resolution than an authentic cadence (V → I) because IV is a larger interval away from I than V is. What is wrong with this reasoning?
A phrase ends with the chord progression V → I, both chords in root position, and the melody note on scale degree 1. What type of cadence is this, and why does it produce the strongest sense of closure?
A composer wants to end a phrase so that the music feels suspended, signaling that more music must follow. Which cadence type best achieves this, and on what chord does the phrase end?
Recap
Chords carry tonal functions—tonic, subdominant, dominant—and cadences punctuate phrases; the dominant's leading tone and tritone generate tension, while the four cadence types control where a listener feels closure or suspension.
Reflect
When has a delayed or deceptive ending in music surprised you, and why?
Music