Sometimes when we talk about periods of music, we're looking at history. But not today. In this lesson, we'll look at periods as a compositional element and see how they help resolve musical tension.
Periods in Music
Roses are red; Violets are blue; You're in my head; I'm in love with someone else, so yeah.
Not a very satisfying ending, is it? Apart from just being heartbreaking, it breaks the rhyme and meter structure, and that's very off-putting. When we create poetry, we like it to resolve and complete the patterns established by its tone, meter, and rhyme. Failure to do so is just…unsatisfying.
Music is the same way. When we compose music, we build patterns of chord progressions and motifs of musical themes. A good composition builds up musical tension and then finds satisfying ways to complete or resolve it. One way to do this is with periods. Periods are sections of music that combine two or more phrases in a very satisfying way. Phrases, in this case, are musical motifs or ideas. So, if roses are red and violets are blue, periods and phrases help music conclude.
Parts of Phrases and Periods
In musical composition, a period is a set of two or more phrases that resolve in a very satisfying way. So, first we need to fully grasp the concept of a phrase. A musical phrase is a motif, idea, or theme that ends in a cadence (a set of notes that brings that musical thought to a close). The cadence is what lets you know that that idea is over; it's like the period at the end of a sentence.
A period combines two or more of these phrases and generally does so in a specific way. The first phrase in a period is known as the antecedent phrase. This phrase introduces a musical idea but ends in a cadence, which is more like a semicolon than a period. It doesn't fully resolve the thought. We call this a half cadence.
It's important to also understand that the second phrase of your average two-phrase period is responsible for completing that thought. This is the consequent phrase, and it almost always ends in a perfect authentic cadence. By the name, you should be able to guess that this is a really good cadence. In basically every song you'll ever hear with a tonal center (from rock 'n roll to a classical symphony), the last two chords create a perfect authentic cadence. This is an extremely satisfying way to resolve musical tension.
Take a look at this diagram. This is a basic format of a period, with HC being a half cadence, PAC being a perfect authentic cadence, and IAC being an imperfect authentic cadence. So, when we pull all of this together, we see that a period is a section of music containing multiple phrases where the last cadence is the strongest.
Of course, music would be no fun if there were only one way to do this. There are many kinds of periods, but let's focus on the three most common.
First is the parallel period. A parallel period contains two phrases which are nearly identical in every way, except the cadence. So, both antecedent and consequent phrases start off with the same structure and ideas but then resolve with different cadences. The difference could just be the last two chords, or it could also include a measure or two before the end so that the cadences get the set up they need. Either way, both phrases start the same way, which is what really defines the parallel period. If we were to transcribe this, giving each musical phrase a letter, it would be represented as this:
That shows that we have a phrase (phrase a) and then repeat it with a parallel version of the same idea (a'). The two lines at the end indicate the end of the period.
So, do both phrases in a period need to mirror each other in some way? Nope. When we combine two distinct musical phrases that both start and end differently, we get a contrasting period. In this case, the antecedent phrase establishes one musical idea and half-resolves it, then the consequent phrase introduces a second musical idea and brings the entire period to a satisfying resolution. We could transcribe this relationship as:
So, we've got phrase a and phrase b within the same musical period.
But what if you want to build a period with more than two phrases? There are many ways to do this, but one common form is the double period, which contains four phrases paired into sets of two. As before, you can have parallel double periods or contrasting double periods, depending on whether each pair of phrases begins the same or differently. This set of symbols is basically what that looks like transcribed:
So, we start with antecedent phrase a that ends in a half cadence. The response is consequent phrase b, which ends in a perfect authentic cadence that is generally weaker than you'd expect. The resolution isn't quite there. This sets up the second pair of phrases, with the antecedent phrase a appearing again and finally reaching a powerful and fulfilling cadence in consequent phrase b'. Since both pairs of the period started the same way (with antecedent phrase a), this is a parallel double period. Use it right, and it's more than just punctuation. It's pure poetry.
Let's review what we've learned about the main periods in music. In musical composition, a phrase is a musical idea or theme that ends in a cadence, with a cadence being a set of notes that creates resolution. Phrases can be combined into periods, or sets of musical ideas that contain multiple phrases and cadences, where the last cadence is the strongest and most satisfying. In a period, the first phrase is the antecedent phrase, which generally ends in a half cadence, and the second is the consequent phrase, usually terminating in a perfect authentic cadence.
There are three primary ways to arrange periods. In a parallel period, both phrases start the same way but end in different cadences. In a contrasting period, both phrases start and end differently. And finally, in a double cadence, four phrases are paired into two sets of antecedent-consequent. There are other ways to mix this up, but that's the basic gist. It's a satisfying way to make musical poetry.