For many people, listening to music elicits such an emotional response that the idea of dredging it for statistics and structure can seem odd or even misguided. But knowing these patterns can give one a deeper more fundamental sense for how music works; for me this makes listening to music a lot more interesting. Of course, if you play an instrument or want to write songs, being aware of these things is obviously of great practical importance.
In this article, we’ll look at the statistics gathered from 1300 choruses, verses, etc. of popular songs to discover the answer to a few basic questions. First we’ll look at the relative popularity of different chords based on the frequency that they appear in the chord progressions of popular music. Then we’ll begin to look at the relationship that different chords have with one another. For example, if a chord is found in a song, what can we say about the probability for what the next chord will be that comes after it?
To make quantitative statements about music you need to have data; lots of it. Guitar tab websites have tons of information about the chord progressions that songs use, but the quality is not very high. Just as important, the information is not in a format suitable for gathering statistics. So, over the past 2 years we’ve been slowly and painstakingly building up a database of songs taken mainly from the billboard 100 and analyzing them 1 at a time. At the moment the database of songs has over 1300 entries indexed. The genre and where they are taken from is important. This is an analysis of mainly “popular” music, not jazz or classical, so the results are not meant to be treated as universal. If you’re interested, you can check out the database here. The entries contain raw information about the chords and melody, while throwing out information about the arrangement and instrumentation.
We can use the information in the song database to answer all sorts of questions. In this introductory post, I’ll look at a few interesting preliminary results, but we invite you to propose your own questions in the comments at the end of the article.