By Ricky O’Bannon

If you listen to music, you instinctively know that a song sounds different the tenth time you hear it from the first. Repetition is an often overlooked yet powerful part of the way we process music, whether that music is a classical symphony or that Taylor Swift song we just can’t seem to get out of our head. 

The Science of an Earworm

We’ve all heard a song on the radio or in the supermarket that we can’t escape. We might even hate the song the first dozen times we hear it, but a few weeks later we find ourselves singing along or maybe even giving in and buying the song.

Elizabeth Hellmuth Margulis directs the music cognition lab at the University of Arkansas and has spent a lot of time investigating why repetition has a profound effect on us. One root cause is what psychologists call the “mere exposure” effect. We tend to like things that we’ve either consciously or unconsciously encountered before, and this applies to food, shapes and music. Psychologist Carlos Pereira found that there is more activity in the emotional regions of our brain when we are listening to music we are familiar with — even if we don’t like the music.

Elizabeth Hellmuth Margulis
Elizabeth Hellmuth Margulis

But beyond just the mere exposure effect, Margulis said that one of the reasons this kind of repeat exposure can cause that earworm to burrow in our mental soundtrack is because repetition actually changes the way we listen to music.

“Repetition changes the way we orient to sound,” Margulis said. It tends to draw us into a participatory stance so that we’re imagining the next note before it happens.”

Music critics and a lot of music fans tend to write off an overly repetitive pop song as trite. But because repetition can make us listen differently, it can also make us pay more attention to some of the more subtle and artful aspects of the music because our mind is no longer occupied with just trying to process the main melodic or harmonic content.

“It [can] shift our attention to lower or higher level aspects of the sounds structure — levels where lots of the richest musical content resides,” Margulis said.

In the case of a pop song, that means we might notice an intriguing bass or drum line that we didn’t hear at first when we were only trying to process the singer’s melody and lyrics. In some cases we might enjoy that earworm because we have taken the time to appreciate the musical content more closely than a song we’ve only heard a few times.

This different kind of listening also applies to classical minimalist composers like Philip Glass, Steve Reich or Terry Riley. Composers like Glass repeat melody and harmonies often ad nauseum, and the effect actually causes the listener to look past those areas where we normally focus our attention to notice subtle variations in each repetition on the micro level or the overarching structure or grand builds on the macro level. 

Repetition Seems Human

In a study at the Music Cognition Lab, Margulis and her team had participants listen to two sets of music. One set was music by 20th-century composers like Luciano Berio and Elliot Carter — composers who intentionally avoided repetition in their works. The other set was digitally altered versions of these composers’ works that were edited to loop and repeat in places.

Margulis writes about her experiment that the listeners reported that they found the altered versions more enjoyable and “more likely to have been composed by a human artist rather than randomly generated by a computer.”

“Repetition serves as a handprint of human intent,” Margulis writes about her experiment. “A phrase that might have sounded arbitrary the first time might come to sound purposefully shaped and communicative the second.”


Repetition Correlates with Popularity

Andrea Ordanini and Joseph Nunes analyzed more than 2,400 pop songs over 50 years. Their study, based at the University of Southern California, found that there was a strong correlation between the number of times a song repeated its chorus and the popularity of that song.

More repetitive songs were more likely to chart in the Top 40. In fact each repetition of the chorus increased the likelihood a song would make it to the Top 40 by 17 percent and increased the chance it was a #1 hit by 14.5 percent. It’s impossible to measure all of the factors that make a song “catchy,” but each repetition of a chorus seems to make it more likely that song becomes that inescapable earworm that we mentally sing and want to hear again and again.

But this study looked at pop music, which has different goals and elements than classical music. Does repetition have a similar power in the popularity of classical music? A survey of the classical music performed during the 2014-2015 season by the largest 22 American orchestras suggests that repetition could at least be a factor.

Several of the most performed pieces arguably use repetition as a major composition technique. Mussorgsky’s Pictures at an Exhibition repeats a “promenade” theme five separate times as either an introduction or interlude between movements, Tchaikovsky’s Symphony No. 5 repeats a central “fate” theme across all four movements, and the repeated four-note motif (dah-dah-dah-Dah!) of Beethoven’s Symphony No. 5 is pounded into the listener’s memory and has become the most recognizable theme in classical music. Just outside the top 10 is Ravel’s Bolero, a piece built entirely around the repetition and variation of a single melody.

Nearly all music classical and otherwise uses repetition, but there is evidence that increased repetition makes it all the more likely we might leave the concert hall whistling that one inescapable melody — and then in turn be all the more likely to want to hear that piece again.

“I think these are basic psychological tendencies that influence our experience whether we’re listening to Taylor Swift or Mozart,” Margulis said.