Cadences in Music: Plagal, Authentic, Deceptive, Half Cadence
All About Cadences
Listen to a piece of music that ends with chords and it’s very possible that what you are hearing at the end is a cadence. This is combination of chords that harmonize with one another and end with a strong beat. Think of them as being a musical version of punctuation such as a period that comes at the end of a sentence, or the question mark at the end of a question that leaves you waiting for the response, and you’ll be on the right track for understanding how cadences are used by composers.
There are four main types of cadence that you may encounter in your piano playing:
The authentic cadence is the more identifiable of these, and there are two types of cadence that fit into this category; the perfect authentic cadence (PAC), and the imperfect authentic cadence (IAC).
A perfect authentic cadence progresses the harmony from a V-I chord and both must be in their root position – although you can add a 7th to the V chord if you want to give a little variation. The final ingredient for the PAC is that the melody must end with tonic pitch. The rules that govern the PAC makes this particular cadence give a clear ending – as in an exclamation mark.
The imperfect authentic cadence is far less restricted. The harmony V-I chord with optional 7th is the same, but then there is more choice as regards whether to invert the chord, and how to end the melody. Slightly weaker than the perfect authentic cadence, the IAC acts more like a period at the end of a sentence, rather than the one at the end of a chapter.
A deceptive cadence (also known as a DC) doesn’t finish up by a fourth as in the V chord on the perfect cadence, but instead resolves only up a second. Although it isn’t used in tonal pieces, it does nicely resolve minor key compositions into major key endings, or vice versa.
In a half cadence, the musical phrase doesn’t end. It is more of a slight pause used before moving on, a transitional chord. The one chord that must be present in a half cadence is the V chord. You can choose whichever chord suits your music best to proceed and follow, but the V is mandatory. There is another type of half cadence known as the phrygian half cadence that was used frequently during the Baroque period, but you will only find these in minor keys and may identify them by the inverted iv chord resolving to a root V or V7. One of the most common areas to find a phyrgian half cadence is at the close of the slow movement of a concerto where it announces the end of that movement but doesn’t allow an extended break before beginning the next.
Finally the plagal cadence is what you will recognize as the “Amen” chord sequence at the end of a hymn, and is created using a IV-I chord regression.
Cadences are hard to identify by simply looking at the music, but play the end chord sequence and you should learn to recognize the more common types of musical closure. Train your ear to listen out for them, and you’ll soon be able to tell your half cadence from a perfect cadence, and deceptive cadence from a plagal cadence.