Even unapologetic Top 40 hit-lovers would have a hard time denying the claim that popular music, on the whole, tends to sound pretty repetitive. This assertion feels so intuitive, that even detailed scientific studies backing it up tend to be met with a shrug. While hardly indicative of Good Art, repetition and simplicity aren't all bad. In fact, most listeners tend to seek a balance of familiar and new, two factors that "influence not only how we perceive popular music, but also how it is produced," according to researchers behind a new PLOS One study that examines how a style's musical complexity increases or decreases over time in relation to album sales.
Perhaps unsurprisingly, the Medical University of Vienna, Austria, scientists found that the more popular a musical style grew, the more generic it became—partly due to the glut of artists that flock to a burgeoning sound and the drop-off in innovation that tends to accompany demand.
The study looked at the "instrumentational complexity" of more than half-a-million albums from 1955 to 2011, across 15 genres and 374 styles as diverse as "hyphy," "viking metal," "acid jazz," and "Korean court music." Within those styles, researchers analyzed the use of nearly 500 instruments. Styles that used generic instruments found in many other styles had low complexity, while styles with a wider array of instruments that were used in fewer styles had high complexity.
Perhaps most interesting is the study's tracking of "complexity life cycles." For one, "experimental," "folk," and "folk rock" consistently maintained high levels of complexity through each time period studied. Others weren't so lucky: "Soul," "classic rock," and "funk" started out high on the complexity scale but have since plummeted.
At different points in time, styles such as "euro house," "disco," and "pop rock" decreased in complexity, but enjoyed higher average album sales, while "experimental," "alternative rock," and "hip hop" became more complex, but saw overall sales decline. "This can be interpreted," the researchers said, "as music becoming increasingly formulaic in terms of instrumentation under increasing sales numbers due to a tendency to popularize music styles with low variety and musicians with similar skills." (In terms of instrumentation being the key here—and the study only looked at complexity factors that lent themselves to quantitative analysis such as acoustics and timbre).
Another caveat: The study pegged its definition of "popular" to album sales, specifically Amazon SalesRank data on average sales for a given style as of 2006. The usefulness of album sales as a metric has been increasingly vexed: 2014 just barely missed becoming the first year without a platinum record (thanks, Taylor Swift's 1989). And unlike some studies, this one doesn’t try to explain how different musical mechanisms (such as the emotional import of minor chords) account for likability or popularity.
The authors acknowledge that the success of a song or album has little to do with its complexity or quality, and more to do with social influence, or what other people seem to enjoy listening to. As Derek Thompson noted in The Atlantic's December's issue, the ability to track nascent hype has translated into bigger returns for the industry, which is seeking newer, data-driven ways to spot the next "Royals" without boring listeners with too much of the same. In other words, labels are looking for that sweet spot between inventive and comfortingly ordinary.