Is music becoming more and more repetitive? Part 2: Chords

It's all one big lump of monotonous trash – really? Part 1 in this series was about lyrics. One study showed how lyrics are becoming increasingly repetitive. A hint towards disappearing diversity in music – but not conclusive proof.

This time we're looking at the music itself. Analysis on this topic is significantly harder.

In truth, I'm trying to answer two questions:

1. Are songs becoming simpler? (Repetition and similarity within a song)
2. Are songs slowly becoming more similar? (Repetition and similarity across songs)

The latter question is more relevant to our investigation. But to answer both, we first need to know how to measure the complexity and themes of a single song.

The harmonic structure of a song

Back when I took guitar lessons, I had to write down the chords of a song – to train my ears in order to better play the song. This also gave me a pretty good overview of the structure of a song – and its complexity.

There are songs with only one chord, even if they're very rare. Here's «Electric Avenue» by Eddy Grant, for example.

Somewhat more frequent, but still rare are songs with only two chords. One notorious example is «Born in the USA» by Bruce Springsteen.

A typical three-chord song: «Get Back» by the Beatles.

«Knocking on Heavens Door» by Bob Dylan has four chords.

Despite its four chords, «Knocking on Heavens Door» is still very simply composed and by no means more varied than «Electric Avenue» or «Born in the USA». The number of chords is an indication towards the complexity, but nothing more – nothing conclusive on its own.

This all becomes somewhat more meaningful when we count not only the chords but the chord sequences. «Knockin On Heavens Door» only has the one, significantly increasing its monotony:

G D | Am | G D | C

For the less musically-inclined: one bar of G major and D major, one bar in A minor, then G and D again, ending with one bar in C major.

Unfortunately, the number of chords can't always be clearly determined. Depending on whether chords are written down in extreme detail or simplified, a song can have more or less chords. For example, listen to «Stairway to Heaven» at 5:35:

What happens in the five second span between 5:35 and 5:40, I would classify as three different chords. But you could also interpret this sequence as a single chord underlying a small multi-chord melody.

Automation or do it yourself?

When showing the development of music over the decades, you'll need a lot of material. If chord complexity is to be investigated, you'll easily have to comb through thousands of songs.

There are tools for music analysis that automatically recognize chords. The Chordify service uses such a tool. This makes analysing large quantities of music simpler. Without computer assistance, this process would be very costly and would take a correspondingly long time.

However, tools such as these make mistakes, and quite a few at that. The computer-generated version of «Killing Me Softly», for example, is wrong across the board. You can easily recognize this by the fact that the A.I. inserts chords where there aren't any at all (only drums and vocals). After «Killing Me Softly» was reworked twelve times (!) manually, the chords seem to be in tune. Less known songs, on the other hand, will remain wrong.

Therefore, a man named Dave Carlton took the trouble to analyse 1,300 well-known songs bit by bit. The majority of them come from the top 100 of the American chart listings. You can view and listen to their structures online.

Carlton made some interesting discoveries. Be these the most common key (not surprisingly: C major), the most used chord sequence (I-V-VI-IV, in C major this would be C, G, Am, F) and which songs use this chord sequence.

The investigation doesn't take the year a song was written in into account. Therefore, it can't say whether harmonies are becoming simpler and more monotonous. Anyway, the songs in question seem to have been chosen quite arbitrarily and only up until 2011.

Standard chord sequences aren't a bad thing

The chord sequence I-V-VI-IV mentioned above is the same as the one used in dozens of songs featured in the following video. From «Let It Be» by the Beatles through «No Woman No Cry» by Bob Marley to «Paparazzi» by Lady Gaga. They're followed by songs with the same chords, just in a different order.

The video is certainly an eye-opener for many. However, claiming that everything sounds the same, as it says in the description of the video, just isn't true. First, most of these songs don't just consist of this chord sequence, it's just a part, the chorus being the most common. Secondly, the chord sequence isn't the only thing that defines a piece. The rhythm, tempo, instruments used or the way the piece is sung are just as important.

There's a reason why I-V-VI-IV is the most common chord sequence. It just sounds good. It's not flashy and doesn't stand out, just the reason I can listen to it any day. The chord sequence is like good bread. A very unusual chord sequence like the one in «Smells Like Teen Spirit» by Nirvana is more like a spice on the other hand. It offers variety, but too much of it isn't good for you. The four chords E A G C don't fit into a key together and therefore result in a less harmonious feel.

Composers don't have to reinvent the wheel. We all use the same twelve notes. What we refer to here as repetition or uniformity can be boiled down to tradition, or the realisation that certain things simply work better than others. Jazz and blues contain standard chord sequences; in blues, the basic structure of a chord sequence is even a prerequisite for the genre as a whole – even if there are numerous variations on the standard scheme.

Further opportunities

I haven't found a study that used chords to justify whether popular music is getting more and more boring. But I won't give up that easily. There are further studies and other ways to determine the complexity of a piece of music. For example:

• The song structure: how many different parts does the song consist of? How similar or how different are these parts?
• Rhythmic complexity: how many different rhythmic patterns are there? Does the song contain syncopations, triplets or even tempo or bar changes?
• Sound complexity: how many different instruments are there? Do they use different effects? Does the instrumentation change or remain the same?

We'll learn more about this in the next part of this series (if you click on Follow author, you certainly won't miss a thing).

By the way: all songs mentioned in this series can be found in this Spotify playlist. It will be updated regularly.