How Has Music Changed Since the 1950s? A Statistical Analysis

How has music composition evolved over time?

Jailhouse Rock (1957). Credit: MGM Pictures.

Intro: Print Music and Sleepify 

For 400 years, music publishing was dominated by sheet music (printed notes and lyrics). The earliest known sheet music was a set of liturgical chants published in 1465, shortly after the Gutenberg Bible. Before the printing press, a composer's works had limited geographical reach, with music access limited to moneyed aristocrats. The advent of industrial music printing enabled an artist's work to be archived and distributed globally at a relatively low cost to consumers. The printing press would be the first technology to disrupt the music industry.  

Flash forward to 2014. Spotify and iTunes exist, while sheet music is used exclusively by band geeks and symphony orchestras. The Michigan-based funk band Vulfpeck releases Sleepify, a ten-track album devoid of audible sound. Each track runs 30 seconds long and consists solely of silence. Sleepify is distributed via Spotify, where the band encourages fans to play the album on a loop while they sleep.

At the time of Sleepify's publication, Spotify paid a rate of $0.0030 to $0.0038 per stream lasting 30 seconds or more. In total, Vulfpeck's album received 5.5 million track listens for a tidy profit of $19,655. Somehow, three hundred seconds of silence became a rousing commercial success—as far as streaming economics were concerned.    

Since the time of printed compositions, music publishing has seen numerous mediums come and go: live performance, radio, vinyl, cassette tapes, music videos, CDs, Napster, Limewire, iTunes, Pandora, Spotify, Youtube, Apple Music, and TikTok. With each change in distribution, artists adapt their acts to reflect shifting consumer preferences. So, how has popular music changed throughout the years? And how have various technologies impacted the content produced by musicians?

Methodology: How Has Popular Music Changed? 

Our analysis will track changes in song composition for popular music over the last seven decades. We'll define popular songs as works listed on The Billboard Hot 100 and utilize Spotify's database of song attributes to track changes in music design.

Our analysis makes use of the following features from Kaggle’s Billboard and Spotify datasets:  

• Billboard Top 100:

  • Song tenure on charts

  • Number of artists on the charts

• Spotify Song Attributes:

  • Song duration

  • Danceability

  • Instrumentalness

  • Speechiness

  • Valence (Song Positivity)

Is the Length of Popular Music Changing?

In the late 1950s, the 45-rpm (revolutions per minute) record format overtook the inelegant 78-rpm design, expanding average music capacity from 4–5 minutes per vinyl side to 9–12 minutes. This increase in revolution time would be the first of many innovations in audio storage. The second half of the twentieth century saw rapid advancement in form factor and storage capacity as album design progressed from vinyl to cassette to CD. As time constraints disappeared, average track lengths increased, with popular song duration peaking in the mid-1990s. 

Looking at artists with hit songs of above-average duration, it's clear the 1980s and early 1990s were a time of unconstrained creative freedom (for track duration, at least).

Streaming was a distant threat; records and cassettes were the predominant distribution format, and music videos encouraged in-depth storytelling alongside hit songs. Everybody wanted their MTV and didn't seem to mind how long music lasted (when paired with pleasing visuals).

And then, starting in the late 1990s, song length began to dip. There are numerous theories regarding the shortening of popular music. The first (and laziest) theory is that consumer attention spans fell. That may be true, but shorter attention spans are usually an output rather than a causal factor (you can't just say people are stupid because they're stupid).

Likely, the fall in song duration stems from two paradigmatic shifts in music economics. First, the introduction of iTunes and streaming led to a decoupling of songs and albums. Artists began focusing on the commercial maximization of individual tracks over cohesive album concepts. Second, streaming services moved the industry toward a pay-per-play revenue model, rewarding artists for the number of listens as opposed to total listening time. Streaming ten 31-second tracks pays more than a single stream of a 310-second song.   

Is Music A Winner-Take-All Market?       

Music exists in an attention economy that connects consumers (who have free time) to artists (who wish to occupy that free time). As such, musicians are perpetually fighting for consumer mind share, much like filmmakers, political pundits, reality TV stars, and documentarians. Until recently, record labels were an overwhelming determinant of an artist's reach, as a cartel of brands functioned as gatekeepers for physical music distribution (determining which artists merited an album release on CD or vinyl). And then Spotify came along. 

Spotify and musicians exist in an unhappy marriage marked by asymmetric power dynamics. Spotify emphasizes its role as a democratizing force in the music industry, offering consumers limitless song selection and providing musicians with easier distribution (free from gatekeeping record labels). I always assumed this last point was a way to obscure streaming's negative impact on artist compensation. However, it appears that the democratization argument holds some weight.

From the 1950s to the mid-2010s, the average number of weeks a hit single spent on the Billboard Hot 100 continuously increased, while the number of artists reaching the charts either decreased or remained relatively constant. In the mid-2010s, as streaming began its rise, a noticeable trend emerged: song tenure declined while the diversity of artists on the charts increased.

Today, more artists make the charts for shorter periods of time. Maybe Spotify isn't all that bad. 

Is Music More or Less Dance-y?

What makes a song danceable? And what does it mean for "danceability" to change over time? People were fox-trotting, jitter-buggings, and tango-ing long before the days of algorithmic party playlists, Bruno Mars, and EDM. It's not like people in the late 1950s abstained from dance because they were waiting for Outkast or Lil Baby. No, they listened to Bobby Darin and Elvis and thought, "Wow, I love dancing to this sufficiently danceable music."

And yet, according to Spotify's "danceability" scoring, popular music has become increasingly danceable over time: 

So what is driving this purported uptick? A few theories:

1. Recency Bias in Spotify's Scoring Algorithm: Popular dance music typically exists within distinct cultural epochs (50s Doo-Wop, 60s Motown, 70s Disco, etc.). Would you expect the same playlist at a wedding and a nightclub? No. Nightclubs cater to younger audiences and promote dance by playing the latest electronic music, hip-hop, and rap. On the other hand, weddings serve a broad age range, often catering to older demographics by playing from a list of well-worn classics (like "September" by Earth, Wind, and Fire). Spotify's song scoring may favor newer music that reflects contemporary dance trends.

2. The Importance of Live Music: The digitization of music distribution offers consumers content abundance in return for a tidy and affordable subscription fee. In response, music acts have shifted their profit centers from record sales to live performances. And what do people like to do at music shows? Dance (while wearing a flower crown)! Hip-hop, rap, and electronic music are cheap to produce and easy to promote, thus fetching increased attention from record labels and concert promoters.       

3. Industrialization of Music Production: In 1998, Cher's mega-hit single "Believe" made prominent (and ear-punishing) use of auto-tune. This new-fangled computerized effect became a focal point of the song's appeal and served as a watershed moment for the mechanization of music production. Since then, audio engineering has become increasingly computerized, with major labels adopting digital workflows, while programs like Logic and GarageBand have democratized production for aspiring musicians. Artists have gradually converged on a homogenized sound for hip-hop, rap, and electronic music, utilizing technology to produce optimally danceable beats.

4. The Rise of Hip-hop and Rap: Sorting through our artists repeatedly featured on the Billboard Charts, it appears Spotify's algorithm categorizes modern hip-hop and rap as the most danceable music genres:  

Meanwhile, Spotify’s feature rankings classify traditional pop (from the 1950s and 1960s) and soft rock as the least danceable music format.

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Where Did The Instrumentals Go?

In rock DJ-ing, there is a time-honored tradition known as the "toilet track"—a selection of well-known, long-running songs that give radio disc jockeys enough time for a bathroom break. Lynard Skynard's "Freebird," Queen's "Bohemian Rhapsody," and Led Zeppelin's "Stairway to Heaven" are prototypical examples of high-quality toilet tracks with extended guitar solos. However, the toilet track may be a thing of the past.

Spotify's "instrumentalness" and "speechiness" scores indicate that unaccompanied instrumentals have become less prevalent over the past thirty years, while lyric-driven music has become much more common.

When we analyze artists with significant speech and instrumental content, we find that rap artists dominate the former category (chart 1), while guitar-driven rock acts lead the latter (chart 2). 

Perhaps it's a stretch, but the fall of instrumental music underscores rock's declining influence, and the rise of speechiness emphasizes rap's growing cultural dominance. Rock and roll is dead—long live rock and roll.  

How Have Music Vibes Changed?

One temptation when reading the tea leaves of our Spotify data is to say that everything sucks. Music used to work, and now it's broken—what a bummer. The continuous decline in song positivity provides yet another tantalizing data point in support of music nihilism

However, I don't interpret this chart as evidence of music's ever-darkening worldview. Instead, my hot take is that modern music better reflects our complicated everyday experiences. Consider the list of artists deemed highly positive by Spotify's "valence" score: 

We can split this roster of musicians into two camps: artists in 1950s America and 1970s dance jams. 

1. 1950s America was the age of Leave It to Beaver, I Love Lucy, the Jim Crow South, TV couples sleeping in separate beds, and Joseph McCarthy's Red Scare. Media was overly-positive, prohibited from addressing complex emotions or social phenomena, with explicit content facing a militant ban from the airwaves.  

2. 1970s dance jams are a relic from the days of disco. These songs induce euphoria, not profound introspection. I have never listened to Donna Summer or Kool & The Gang and thought, "This song is giving me feelz," or "I now possess a nuanced understanding of the human condition." No, I typically listen to these bands and think, "Wow, this DJ is crushing this Bar Mitzvah."  

As means of comparison, consider Blink 182's "Adam Song," which represents a stark emotional departure from the abovementioned music. Released in 2000, "Adam's Song" takes the form of a fictional suicide note and was intended to inspire optimism for those struggling with depression. Many with mental health struggles have cited a profound connection with the song and its ultimate message of hope. I highly doubt "Adam's Song" would make it to the airwaves if released even a few years earlier.   

Final Thoughts: The Ever-Changing Medium and Ever-Responding Message    

Sabrina Carpenter’s “Espresso” Music Video. Credit: Island Records.

Canadian philosopher Marshall McLuhan is well-known for prophesizing a fragmented media landscape defined by ever-changing advances in distribution. His theories seem inevitable in today's world of content abundance; however, McLuhan was writing in the 1960s, when people bought Elvis records, watched four TV channels, and knew nothing of Elon Musk. Simpler times. 

In his book Understanding Media, McLuhan highlights the transformative power of technological progress (which he broadly terms "media" or "medium" ):  

"The medium is the message. This is merely to say that the personal and social consequences of any medium - that is, of any extension of ourselves - result from the new scale that is introduced into our affairs by each extension of ourselves, or by any new technology."

According to McLuhan, technological progress "shapes and controls" human interaction, not any one piece of content distributed via these new-fangled platforms. So, for example, the advent of social media spurs a change in human relations, not any one tweet that follows. 

Streaming offers a world of democratized music distribution and consumer abundance. Musicians can easily disseminate works in a market characterized by increased artistic control, and for $9.99 a month users get access to every song in human history. Today's music industry, from songwriting to album promotion, is thus organized in service of a recurring $10 price commitment.   

And with that, let's return to Sleepify—sweet, wonderful, Sleepify. While overwhelmingly bare in content (or lack thereof), Sleepify's success epitomizes (and mocks) music's maniacal quest to maximize time consumption. In this extreme case, a silent album generated nearly $20k in earnings but would have sold zero copies of sheet music in the late 1400s. How times have changed since Renaissance Italy.

Vulfpeck's muted masterpiece is uncomplicated yet far-reaching in its message, as the album required minimal production, simultaneously critiqued and exploited Spotify's business model, and made decent money in the process. It's also an example of artists acknowledging the regrettable business dynamics of streaming while simultaneously adjusting to the new norm. 

Streaming is here to stay—until the next disruption in music distribution. The artists who adapt their message will conquer the new medium. 

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Want to chat about data and statistics? Have an interesting data project? Just want to say hi? Email daniel@statsignificant.com