Authentic, Half, and Plagal Cadences

A. Authentic cadence

The dominant to tonic resolution at the end of a phrase is an authentic cadence.

• If the soprano moves from re’ – do’ or ti – do’, it is a perfect authentic cadence (PAC).

• If the soprano ends on anything other than do, it is an imperfect authentic cadence (IAC). Possibilities for the soprano are r – m, f – m, s – s, or s – m.

B. Half cadence

If a phrase ends on the dominant triad V, it is a half cadence (HC). Due to its open-ended nature, the half cadence creates an expectation for a subsequent phrase or phrases, which conclude with an authentic cadence.

Typical approaches to the half cadence are  IV⁽⁶⁾ – V and ii⁽⁶⁾ – V. The V chord can be prolonged by the [I ] – V formula.

A half-cadence in harmonic minor between iv⁶ – V is called a Phrygian cadence. The bass resolving a half step down suggests the final two notes of the descending Phrygian modal scale (fa – mi), thus providing the name. (See the chapter on modal music.)

C. Plagal cadence

If a phrase ends with the subdominant moving to the tonic, it is a plagal cadence (PC), also known as the “amen” cadence. The plagal cadence typically follows a PAC.

Deceptive Resolution – Deceptive Cadence

Deceptive resolution

The resolution of V – vi  in major and V – VI  in minor is a deceptive resolution.

1. In major keys, if the V⁽⁷⁾ chord does not resolve to the tonic triad it may resolve to its substitute, the vi triad, in contrary motion.
2a. In harmonic minor, contrary motion is not possible due to the presence of the ti – le A2.
2b. To avoid the A2, ti – do and re – do resolve to a VI  triad with doubled thirds do/do.  The VI  chord, with its octave or unison doubled third, sounds “deceptively” similar to the tonic chord.
2c. The deceptive resolution of V⁽⁷⁾ – vi  produces the same “deceptive” tonic-like effect in major keys.

Deceptive cadence

3. When the deceptive resolution is employed to end a phrase, it qualifies as a deceptive cadence. The deceptive cadence is either V – vi   or V⁷ – vi . The resolution of V – IV⁶ with ti – do in the soprano produces a somewhat similar deceptive effect.

The deceptive resolution occurs within a phrase.

The deceptive cadence occurs at the end of a phrase.

Composers employ the deceptive cadence at the end of compositions to create an expectation for the final PAC or as a longer ending coda with a final PAC.

VOICE LEADING: Deceptive Resolution/Cadence

All progressions work in major and harmonic minor.

The similarly deceptive V – IV⁶ (iv⁶ in minor) is also shown above.

The similarly deceptive V⁷ – IV⁶ (iv⁶ in minor) is also shown above.

Other Uses of the Deceptive Resolution

The reverse of the deceptive resolution I – vi  – V or I – IV⁶ – V produces an attractive soprano line (so – do’ – ti).

The vi  and IV⁶ can appear consecutively to prolong the resolution to V:  I – vi  – IV⁶ – V, shown below in minor.

A less frequent deceptive resolution occurs in major, when the vii^o6 substitutes for the V⁽⁷⁾ chord resolving to a vi  with the doubled third (ti – do, re – do).