Definition
The authentic cadence is the dominant → tonic succession (V–I or V7–I) at the end of a phrase. Not all authentic cadences have the same strength: they are divided into perfect and imperfect according to the arrangement of the chords and the soprano note.
Perfect cadence
A perfect authentic cadence occurs when:
- both chords (V and I) are in root position;
- the soprano ends on the tonic (in C: soprano B → C or D → C);
- the arrival on the tonic occurs on a strong beat.
It is the most conclusive cadence in tonal music: it closes periods, sections, and pieces.
Imperfect cadence
The authentic cadence is imperfect if even one of the conditions is missing:
- the soprano ends on the third or the fifth of the tonic (D → E, D → G);
- one of the two chords is in inversion (V6–I, V–I6, V4/3–I);
- instead of the V there is the vii°6 (dominant without root).
The imperfect cadence closes, but leaves the feeling that the discourse could continue.
Compound cadence
When the dominant is preceded by the cadential six-four (I6/4–V–I), we speak of a compound cadence. Combined with a predominant (ii6–I6/4–V7–I) it forms the most complete cadential formula of the Classical style.
Hierarchy of closures
| Cadence | Strength |
|---|---|
| Perfect (V–I, soprano on the tonic, strong beat) | maximum |
| Imperfect (soprano on the third or fifth) | medium |
| Imperfect with inversions (V6–I, V–I6) | weak |
| Half cadence (ends on the V) | suspensive |
| Deceptive (V–vi) | avoided |
Practical rules
- Reserve the perfect cadence for important formal points: end of the period, end of a section, the finale.
- Use the imperfect cadence to close internal phrases without stopping the flow.
- In voice leading: the leading tone rises to the tonic, the seventh of the V7 falls to the third of the tonic. If the complete V7 resolves to an incomplete I (root tripled and third), it is correct.
- The bass from the dominant to the tonic moves by descending fifth or ascending fourth.
Common mistakes
- Ending a piece with an imperfect cadence without meaning to (soprano on the third): the ending sounds incomplete.
- Putting the arrival tonic on a weak beat.
- Using perfect cadences at every phrase: the music breaks into many closed blocks.
Examples
- Beethoven, “Ode to Joy”: the second phrase ends with the soprano D → C over V–I: a perfect cadence that closes the period.
- Bach chorales: the last phrase almost always ends with a perfect cadence, the internal phrases often with imperfect ones or half cadences.
- Classical symphony finales: the insistent repetition of root-position V–I with the tonic in the soprano makes the closure unmistakable.
- Pop: many intermediate choruses end on an IV or on a I with the third in the melody (imperfect closure); the last chorus closes with the melody on the tonic.
How to use it in composition
- Plan cadences like the punctuation of a text: imperfect ones as commas and semicolons, perfect ones as periods.
- In the chorus melody, choose consciously which degree to close on: tonic to close, third or fifth to leave it open.
- If a piece seems to end too soon, turn an internal perfect cadence into an imperfect or deceptive one.
Exercise
- Write four authentic cadences in Eb major: perfect, imperfect with soprano on the third, imperfect with V6, imperfect with vii°6.
- Analyze the cadences of a Bach chorale and classify them.
- Rewrite the ending of a chorus of your own by changing the final note of the melody and evaluate the effect.
Connections
Cadences; Half cadence and Phrygian cadence; Deceptive cadence and variants; The six-four chord; The period: antecedent and consequent; Dominant seventh chord.