The Function of Cadences in Music
You've probably heard it said that music is a language. And like any language, it has certain elements that help us navigate our way through it. These include phrases, pauses, changes of speed and accent.
A musical phrase might be compared to an English sentence, having a beginning, a main idea and a definite conclusion. The longer the sentence, the more devices used to help us make sense of what's being said, such as punctuation. A sentence written in English will use commas, semi-colons and periods to help us identify pauses and stopping points. A musical phrase will do the same thing using its own unique form of "punctuation" known as cadences.
Cadences are Musical Signposts
Cadences exist in almost every kind of music in the Western world, from classical to jazz and pop. They're in the nursery rhymes and occasional songs we learn when we're growing up, and they form the backbone of a high percentage of the music heard across the globe from day to day.
If you were to write a list of your favorite 10 songs of all time, it's likely that there would be some cadences in every one of them. Even a song like "Happy Birthday" is packed with them, and we'll use that most familiar tune to get started.
Definition of Cadence
The term "cadence" defines the movement (or progression) of two or more chords designed to bring a section of music to an end. Perfect cadences sound final and usually come at the end of sections or at the end of the song. Imperfect cadences sound unfinished and usually come in the middle of a piece or section.
The word comes from the Latin cadentia, meaning "a falling" - although we use the word to indicate when the music comes to a rest either temporarily or finally.
The Basic Cadences
Music, like any language, has to be structured in a way that makes sense. In the same way that you never see sentences or paragraphs written without capital letters, commas and periods, you never come across music that doesn't have cadence points in it. Without these "breathing" points the sentence or musical phrase would simply become a continuous stream of words or notes, incomprehensible for the most part, going nowhere and communicating very little.
Cadences are built around the main chords of a key and the way we expect a song or tune to unfold. In the key of C major, for instance, we expect the piece to start in the key of C and to end in the key of C, C being the tonic. During the middle of the piece it might wander off to the dominant or G, or to the sub-dominant or F. But eventually we know it will return back to the tonic - because that's what music does.
We call the chords of a key by their name and also by the number of the scale they occupy, using Roman numerals. So the tonic chord formed on the first note of the scale is also called the I chord, the dominant formed on the fifth note of the scale is the V chord, and the sub-dominant on the fourth note is the IV chord. Here's an example of the first cadence using two of these chords in the tune "Happy Birthday to You" -
As well as being numbered using Roman numerals, cadences also have specific names. The cadence moving from the I chord to the V chord above is called an Imperfect cadence, and its opposite - shown below - moving from the V chord to the I chord is called a Perfect cadence:
The song continues with a chord progression ending on the sub-dominant, or the chord of C major. Note the F sharp which functions as a passing tone from the notes G to E in the melody:
Finally the piece concludes with a perfect cadence, ending on the tonic or G chord (I) and using a dominant seventh chord (V7) to add variety and color.
Other Common Cadences
There are many other names and variations for these cadences - particularly significant when the chords used are in inversions - but if you know these names at least you have made a beginning. Each cadence can be extended by adding extra chords to it, producing progressions such as the ii-V-I found in the picture at the beginning of this article, which results in a perfect cadence (V-I) but sounds more interesting with the addition of the ii chord beforehand.
Another common twist is to include what's known as a 6/4 chord in the progression. 6/4 indicates a chord in its second position (i.e. for G major that means a D as the lowest note), where the other two notes that make up the chord can be found at intervals of 4 notes (the tonic) and 6 notes (the third of the chord) above the bass note. This makes movement smoother between chords, as progression to a D chord means the bass note stays the same. Here's how that would work in the "Happy Birthday" song:
One of the most famous cadences is the plagal cadence, also known as the Amen cadence. This you often hear at the end of hymns and religious music, when the choir or congregation sings the word "Amen" in a harmonic arrangement using the chords IV and I, as shown below: