AP® Music Theory · Unit 5 · Topic 5.5
Cadences with Predominant Function
A cadence with predominant function stacks a predominant chord, then dominant, then tonic, so the ear feels the dominant arrive as a goal instead of a surprise. That setup is what gives a perfect authentic cadence its full weight.
A cadence is a harmonic arrival, and arrivals feel stronger when you prepare them. Jumping straight from tonic to dominant to tonic works, but adding a predominant chord first, IV, ii, or ii6, gives the dominant somewhere to come from. The predominant chord typically contains the fourth scale degree moving down or staying put into the dominant's root or third, so the bass and the harmony both lean toward V before V even sounds. That lean is why the standard cadential formula orders chords as predominant, then dominant, then tonic: each chord sets up the next, and the tonic at the end feels earned rather than arbitrary.
In four-part writing this plays out in the bass and in the voice leading. Take IV, V, I as a perfect authentic cadence in A flat major: IV is D flat-F-A flat, V is E flat-G-B flat, I is A flat-C-E flat. The bass walks D flat up to E flat up to A flat, outer voices expand to an octave on the final tonic, and the leading tone G in V resolves up to A flat in I. Swap IV for ii6, built on the same fourth-scale-degree bass note, and the label changes but the function and the pull into V stay identical, still ending the phrase on dominant if the phrase stops there rather than resolving to I.
This predominant-dominant-tonic chain is also what separates authentic cadences from plagal ones. A plagal cadence, IV to I, skips the dominant and its leading tone entirely, so it has no half-step pull forcing the ear toward tonic. It can confirm a key already in place, which is why it shows up as an 'amen' gesture after a cadence has already landed, but it cannot establish a new key the way V to I can.
Key terms
- Predominant function
- The harmonic role of chords like IV, ii, and ii6 that lead naturally into the dominant.
- Cadential formula
- The fixed three-stage pattern of predominant, then dominant, then tonic that closes a phrase.
- Perfect authentic cadence
- A V-to-I (or predominant-V-I) cadence with both chords in root position and tonic on top in the final chord.
- Plagal cadence
- A IV-to-I cadence that confirms a key without the leading tone's pull, often used after the key is already set.
- Leading tone
- The seventh scale degree, a half step below tonic, whose pull upward drives dominant-to-tonic motion.
Watch it explained
- How it worksHow does the standard cadential formula stack predominant, dominant, and tonic in order?
- Worked exampleWalk me through a IV, V, I perfect authentic cadence in A flat major in four parts.
- Worked exampleFind the cadence type and the function labels for ii6 to V ending a phrase on the dominant.
- Common mistakeWhy isn't a plagal cadence used to establish a key the way an authentic cadence is?
Check yourself
End of topic.