Evolution of Topics
In this blog I will be using the word topic to describe what the authors of the article, who “investigate the US Billboard Hot 100 between 1960 and 2010. Using music information retrieval and text-mining tools (**) we analyze the musical properties of approximately 17 000 recordings that appeared in the charts and demonstrate quantitative trends in their harmonic and timbral properties. We then use these properties to produce an audio-based classification of musical styles (or topics) and study the evolution of musical diversity and disparity, testing, and rejecting, several classical theories of cultural change.” They say, “Finally, we investigate whether pop musical evolution has been gradual or punctuated. We show that, although pop music has evolved continuously, it did so with particular rapidity during three stylistic ‘revolutions’ around 1964, 1983 and 1991. We conclude by discussing how our study points the way to a quantitative science of cultural change” (Mauch, MacCallum, Levy; 2015).
Now. After I didn’t really focus my attention on that last sentence but I think it kind allows us to speculate what we want because after all… It is a SCIENCE (insert picture of Bill Nye, except don’t because he’s just an actor).
The study ends up showing that throughout the 50-year span of 1960 to 2010 the frequencies of timbral topics and styles in the Hot 100 varies greatly: some became rarer, others became more common, yet others cycle. (which I find very intriguing for a couple reasons) The authors use associations between the topics and particular artists as well as genre-tags assigned by the listeners of a free music listening website Last.fm, a web-based music discovery service with approximately 50 million users (Mauch, MacCallum, Levy; 2015). They split up topics into two groups, H topics and T topics. H topics are classified as topics dealing with harmonic qualities and T topics are for frequencies of timbral topics. That just means T topics are about how the sound is described, or its color, and H topics deal with how the sounds might be created (i.e using certain chord structure). Take a look at Graph 2, it shows a chart of each of the 16 topics and shows the frequency that a specific topic shows up in popular song and what year.
Starting with H topics first, H8 (major chords without changes) nearly 2/3 of the songs show a substantial frequency of this topic. Its presence in the hot 100 was quite constant, being the most common H topic in 43 of the 50 years. If you look at the graph again, you will see this topic start of drop around the time that Rap/Hip-Hop revolution begins to take off. H1 captures the use of dominant seventh chords, which are inherently dissonant (because of the tritone interval between the 3rd and minor 7th), these chords are commonly found in Jazz to create tensions that are eventually resolved to consonant chords. They are also found in blues music, the dissonances are typically not resolved giving it a “dirty” color. Accordingly, the authors find that the decline of this topic, then, represents the lingering death of Jazz and Blues in the hot 100. If you look at H8 on the graph though, It does appear to be on the rise again… Topic H3 embraces minor 7th chords used for harmonic color in funk, disco, and soul and its mean more than doubles between the years 1967 and 1977. H6 combines several chord changes that are a mainstay in modal rock and therefore common in artists with big stadium ambitions (e.g. Motley Crue, Van Halen, REO Speedwagon, Queen, Kiss and Alice cooper). Although not a drastic as the others, H6’s increase between 1978 and 85, along with subsequent decline in early 1990’s, marks the age of Arena Rock. Out of all H-topics, H5 shoes the most striking change in frequency. H5 captures the absence of identifiable chord structure. You can see that it is barely present in the 60’s and 70’s when almost all songs in the top 100 featured clearly identifiable chords. H5 becomes more frequent in the late 80’s and then rises rapidly to a peak in 1993. This is said to represent the rise of Hip Hop, Rap and other related genres, as exemplified by the music of Busta Rhymes, Nas and Snoop Dog, who all use chords particularly rarely (Mauch, MacCallum, Levy; 2015).
Timbral topics also evolve over time. T3, described as ‘energetic, speech, bright’, shows the same pattern has H5 as is also associated with the rise of Hip Hop and related genres. T5 (‘guitar, loud, energetic’) undergoes two full cycles with peaks in 1966 and 1985, headed upward once more in 2009 (HALLELUJAH!!!). The second, larger peak in 1985 coincides with the peaks in H6 we discussed earlier, which are the chord changes subsequent with stadium rock groups. Finally, there is a steady rise until about 1990 in the T1 category, which is ‘aggressive, percussive drums’. The article attributes this with the spread of new percussive technology such as drum machines and gated reverb effect famously used by Phil Collins on In the air tonight, 1981. T1 then begins to dwindle after 1990 marking the reign of the drum machine (Mauch, MacCallum, Levy; 2015).
In the next blog, I talk about the genres that are made up of each of the musical aspects I just talked about and how they change through popular music.
For now I’m dropping the needle on AC/DC’s if you want blood live album from 78’, So Rock on.