In the days since Ted Gioia published his essay in the Daily Beast, alleging that music criticism has devolved into lifestyle reporting, with little or no attention paid to how the music itself works, I've been challenged by friends on Facebook to write a "not boring" piece that explains a successful pop song using music theory. My bet is that it’ll be boring, but I'm going to do my best not to bore you!
I have picked Katy Perry's "Teenage Dream." Because: this song's success seems to mystify all the Katy Perry haters in the world. Why did it go to No. 1? Let’s start by talking about the ingenuity of the harmonic content. This song is all about suspension - not in the voice-leading 4-3 sense, but in the emotional sense, which listeners often associate with "exhilaration," being on the road, being on a roller coaster, travel. This sense of suspension is created simply, by denying the listener any I chords. There is not a single I chord in the song. Laymen, the I chord ("one chord") is the chord that the key is in. For example, a song is in G but there are no G-chords. Other examples of this, in hit singles: Fleetwood Mac’s "Dreams" and Stardust’s "Music Sounds Better With You"; almost-examples include Earth Wind and Fire's "September" which has an I chord but only passing and in inversion; same with Coldplay's "Viva La Vida."