In this chapter we are going to learn a specific type of chord progression called cadence. A cadence is a chord progression that expresses a sense of finality. This sense of finality can be stronger or weaker depending on certain factors. There are three types of cadences: authentic, plagal and deceptive.
The Authentic Cadence
An authentic cadence is movement from ‘V’ to ‘I’ (or ‘V7’ to ‘I’). This is the strongest type of cadence, since ‘V’ has the strongest tendency towards ‘I’. Authentic cadences can be further classified into perfect and Imperfect. Both are considered to be strong cadences, but the perfect is slightly stronger than the imperfect.
A perfect authentic cadence is movement from ‘V’ to ‘I’, with two additional with two criteria that must be met. 1: Each chord must have its root as the lowest pitch, and 2: the final chord must also have its root as the highest pitch. When either of these two criteria is not met, it is considered an ‘imperfect’ authentic cadence. Here is an example of a perfect authentic cadence.
(Chapter 25 – Audio Sample 1)
The preceding example is in the key of C major; where the G major chord is the ‘V’ chord (GDGB) and the C major chord (CEGC) is the ‘I’ chord. As you can see, the root of the ‘V’ chord (‘G’) is the lowest pitch in the ‘V’ chord, and the root of the ‘I’ chord (‘C’) is the lowest pitch in the ‘I’ chord.
Here is an example of an imperfect authentic cadence.
(Chapter 25 – Audio Sample 2)
The preceding example is called an ‘Imperfect authentic cadence’ and is any cadential that ends on the chord ‘V’. The progression from ‘I’ to ‘V’ is the exact reverse of the perfect cadence and is therefore has the opposite effect. If the perfect cadence is considered as a closing gesture- bringing a sense of resolution- the progression from ‘I’ to ‘V’ is an open gesture.
The Plagal Cadence
The plagal cadence is movement from ‘IV’ to ‘I’. It is not quite as strong as the authentic cadence.
(Chapter 25 – Audio Sample 3)
The Deceptive Cadence
With the authentic cadence we had movement from ‘V’ to ‘I’. The deceptive cadence is movement from ‘V’ to a chord other than ‘I’. It is called “deceptive” because the ear is expecting to hear the resolution to the ‘I’ chord, then a chord other than ‘I’ is played. These types of cadences create a sense of suspension. Here is an example of a typical deceptive cadence.
(Chapter 25 – Audio Sample 4)