Perfect authentic cadence

General info

Name

Perfect authentic cadence

Cadence type

Authentic

Sequence

V

I

Chord count

2

Cadence composition in A

Construction logic

A perfect authentic cadence joins dominant V to tonic I. In V⁷, the tritone between scale degrees 4 and 7 resolves by contrary motion: the leading tone rises to 1 while scale degree 4 falls to 3. Both chords are in root position and the final tonic has scale degree 1 in the soprano, producing the strongest authentic close.

How it sounds

A strong, unambiguous close. Root position in both chords and the tonic in the soprano reinforce the stability of the final I.

Harmonic functions

Dominant

Dominant V⁷ contains the leading tone and a tritone between scale degrees 4 and 7. In a typical resolution, 7 rises to 1 while 4 falls to 3.

Tonic

Tonic I represents the stable centre of the key. After V⁷, it receives the resolutions of the leading tone and dominant seventh.

Why it works

Both chords are in root position, and the final I has tonic in the soprano. These conditions distinguish a perfect authentic cadence from weaker authentic closures.

Tensions & resolutions

Harmonic context

A perfect authentic cadence marks strong boundaries of periods and sections. In jazz harmony, V–I is often expanded by predominant ii, while the specific voicing determines the degree of closure.

Variants & extensions

The dominant may be extended to V⁹ or V¹³, supplied with a 4–3 suspension, or preceded by IV or ii. To remain a perfect authentic cadence, V and I must be in root position with tonic in the soprano of the final I.