How does this compare to what Music Theory says about chords and chord progressions? Any Music Theory experts/aficionados around? I've unfortunately forgotten most of what I learned in my one class on it.
He doesn't go nearly enough into depth to say anything surprising. That "C/Am" is by far the most common is not surprising at all; C major is the first key any music student learns.
I wish he separated out the major keys from minor keys. It's easy to tell the difference; almost no-one writes pop music in the natural minor (which shares a key signature with the relative major), as it has no dominant fifth. Rather, melodic and harmonic minor keys are used, which have a distinct key signature from major keys (both have the 7th note of the scale raised to accommodate a dominant fifth chord). This should make them easy to detect.
The "Chord Use" chart also does not say much; C, F, and G are the I, IV, and V chords of the key of C major (the Roman numerals indicating their relative position in the scale), which together form the basic pop progression. Much more useful would have been to bin the chords relative to the key in which the song is written, rather than as their absolute pitch.
What I would also like to see is a histogram of chord progressions, e.g. I-IV-V vs. I-IV-ii-V vs. I-vi-VI-V etc. His preview of next week hints at this, but again he should use relative chord names rather than absolute chord names.
The preview graph, "Chords following em", is not very surprising either. Since this is an absolute chart rather than a relative one, we must assume that the data is reflective of the chord's use in the most common key (C). (Em will rarely occur in a song written in Am; rather, it will be altered to an E7 dominant chord.) Of the other chords available in the key of C, C and G both share two out of three notes with Em and thus are unlikely to be used due to lack of motion between them. Bdim is rarely used in C.
This leaves Dm, F, and Am as likely to occur following an Em. The E and B notes of the Em chord are a half-step below the next higher note in the scale, so they will tend toward upward motion, meaning the next chord will likely contain an F or a C. F contains both of these, hence its prominence in the graph. Both Am and Dm contain one of these notes; however Em->Am is an upward (downward) skip of a fourth (fifth), which is a resolving motion – it is likely that the next few chords following these two will be Dm, G, and C, to continue this motion. Em->Dm, being a skip of a second, does not share this property and hence should not be as common.
I was going to write up pretty much the same analysis of the Em->X progression. I think you aptly covered it. Interestingly, though, as you say Em->C sounds relatively static, I bet you see a lot more C->Em than the reverse (which should suffer from the same problem), and I'm hard pressed to say why exactly.
My guess would be that it's a precursor to an Em->F or Em->Am transition; i.e., if you wanted to transition to a minor mode convincingly from C, you'd toss the Em (or even E7) in there before hitting Am. Example: Santeria by Sublime (I-III-vi-V)
I can't speak for pop music, but you can move from Em to C/E to F, which is basically a delayed resolution of the E to F, but the C Major is definitely there.
Regarding "chords following em": Since all of the songs were transposed to the key of C, em == iii, am == vi, and F == IV. Really what the post says is IV and vi follow iii most often in popular songs.
Well, like the article went into briefly, the I, IV and V chords are going to be the main ones used in a song, especially one from a rock/blues tradition. (a minor, d minor and e minor are the 1, 4, and 5 for a song in a minor key.)
C and a-minor, F and d-minor, and G and e-minor are related chords, and can be interchanged in a standard progression for a different "feel". So it makes sense that e-minor would go to F (V to IV transition) or a-minor (V to I) more than any others. It's interesting that C and d-minor are under-represented in that transition.
It's interesting that the possible chords are all simple triads, with no options for extra tones. A C6 with particular notes in the bass could be interpreted as an a-minor, for example. There's a fair amount of ambiguity there.
Everything in this post is consonant with typical music theory.
The most popular chords are the good old I, IV, and V, and the next most popular are their relative minors (C -> am, G -> em, F -> dm).
The example they give of chords following "em" is also pretty much what you'd expect. The most classic resolution for "em" would be "am" (it's dominant -> tonic in the relative minor key).
The more popular resolution here ("em" to "F") is more of a pop music thing, because it's harder to do classical voice leading with it -- classical composers tended to avoid parallel fifths.
Edited to add: Why mention classical rules at all in a post about pop music? Because there's not much new under the sun -- you'd be hard pressed to find any harmony in pop music that Mozart or even Bach wouldn't recognize.
Good points. Many rules in popular music come directly from classical music (after all, it's been around for a while).
However, as you can see in the Hooktheory database, there are many progressions that seem to be unique to popular music.
You mentioned iii->IV, which is a no-no in classical music due to the parallel fifths (more common: V/vi -> IV). But also look at progressions like: C G Bb F, which is extremely common in pop. Here we have a double plagal cadence set up by the dominant that was never used by Bach or Mozart, which is probably best functionalized as: I V IV/IV IV
I would make the argument that there is little in the way of pop music that strays from traditionally accepted chord progressions. Dissonance isn't something that appeals to a broad audience, and you'll be hard pressed to find someone who can point out an interesting choice in progression for a song on the radio.
Sorry in advance for the pedantry. ;) Dissonance is when notes "clash" with each other and in traditional voice leading dissonance always resolves to consonance.
Atonality, on the other hand, is a more recent development in Western music and is defined as the lack of a tonal center. Atonality can be an extremely interesting way to write music. Some of the first atonal music (note how it's not markedly "dissonant") can be found in Debussy's Prélude à l'après-midi d'un faune[1] and the prelude to act I of Wagner's Tristan und Isolde [2].
I don't listen to a huge amount of pop music, but is there anyone out there that is at least experimenting with atonality?
Sorry, I should have been more clear. I was listing a few things that wouldn't show up on this list and wouldn't be in pop music. Dissonance and interesting chord progressions were the two I called out specifically.
The chord stuff is all perfectly reasonable (in pop music, that is; in a classical piece in the key of C you would have an Em going to an Am way more than to F, for example, and you'd see way more D chords).
I don't buy that Eb/Cm is the third most common key in pop music, though. There's not a whole lot of pop music in minor keys, and Eb is a weird key to play guitar in.
> There's not a whole lot of pop music in minor keys
In my informal survey of the first 6 songs I got on the "pop" channel on pandora, fully a third were in minor keys. (Rumor has it by Adele, and I wanna go by Britney Spears)
I think one of the primary issues with popular music is that it's often ambiguous whether it's in a major or minor mode, even when the song starts on a minor chord. Classically, one would mark the transition to a minor mode by the existence of an authentic cadence: V/vi -> vi, or by the raised scale degree 5, but neither of those clues exist in either song that you mentioned.
In songs like My Heart Will Go On, it appears that the verse tonicizes I, where as the chorus centers around the relative minor. However does it make sense to say it switches modes every time the section changes? Maybe not
