Many pop songs out there are fond of of the number four. A great example of this is The Flaming Lips's song "Turn it On." The chord progression for the verses is D - A - G - D. Four chords, repeated four times. That is a phrase, which can be analagous to a sentence of words. It's one of those "Ummm duh" kind of things, but the verse phrase is repeated until the chorus in many pop songs. There is repetition, which is why I love using this song to teach people guitar. The question is, "How do I know when the chorus will come?" The answer I believe is in the melody. The melody, in this song as well as many great pop songs (The Beatles were masters at this) will give away when the chorus will come.

Of course, you can count the amount of times a phrase is repeated and then switch when the chorus comes around. This is far from fail-safe because what if you forget? If you are on stage and forget the number of times a verse is repeated, and you are staring at some girl in the front row (true story. It happened to me. Embarassing!), then oops. But if you listen to the melody and hear it set up the chorus, then done. Switch, and then you are awesome.

The cool thing also is that there are even more musical cues, beyond the melody, that help give away all the choruses as well. In "Turn it On," the drums do a great job of setting up the chorus. It's fun to listen to drummers when they are playing in a big band (like Duke Ellington or Count Basie) sort of set up the next section. You can hear these cues too. If the intention of the musicians is to set up the parts, you can hear them. It's one of those nice little things that makes listening to music so enjoyable.