Scientists reveal the secret of jazz swing: clips

Saxophonist Joshua Redman is playing in 2019. Swing is a staple in almost all genres of jazz. Physicists believe that subtle nuances in the timing of the soloists are key to creating the impulsive swing feel.

Bernd Theissen/Image Coalition via Getty Image

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Bernd Theissen/Image Coalition via Getty Image

Saxophonist Joshua Redman is playing in 2019. Swing is a staple in almost all genres of jazz. Physicists believe that subtle nuances in the timing of the soloists are key to creating the impulsive swing feel.

Bernd Theissen/Image Coalition via Getty Image

For nearly a century, jazz musicians and scholars have debated the answer to a musical riddle. As legendary trumpeter Louis Armstrong once said, “What’s this thing called swing?”

Swing has long been considered an essential component of almost all genres of jazz, from traditional to bebop to post-bop. As Ella Fitzgerald and many others sang, “It doesn’t mean a thing if you ain’t got that swing.” You might describe swing as a rhythmic phenomenon in jazz performances—a wonderful thrusting feeling that makes you want to move with the music.

However, the precise definition of swing has eluded musicians and scholars alike. It was also reported that Big Band era jazz trumpeter Cootie Williams once joked about swing, “Describe it? I’d rather tackle Einstein’s theory.”

Fittingly, physicists now think they have an answer to the mystery of swinging—and it all has to do with the subtle nuances of the soloists’ timing.


This elusive swing in performances

Ask a jazz musician what an alternative is, and you’ll likely get the same answer Christian McBride gave me.

“Swing is a feeling,” says McBride, a multi-award winning jazz trumpeter, music educator and host of NPR. Jazz Night in America. “There is a certain language. There is a certain inversion of rhythm.”

There is one defining element of swing that is easy to hear, and it has to do with how the eighth notes are played. Instead of playing directly, like this…

… In jazz, these notes are oscillates, which means that the downbeats—or every other eighth note—are played a little longer, while the offbeats in between are shortened, creating a fast beat, like this one.

But jazz musicians know that technology alone can’t explain swing—after all, even a computer can swing a note.

“The computer is not – Excuse my language – it wouldn’t swing that hard, you know? McBride says. You still don’t feel the real right swing, which is a human feeling. “

McBride explains that this oscillating feeling occurs when the musicians interact in a performance. “For me, I think you have to lock people up and say, ‘Okay, here’s the time, here’s the beat.'” And then everyone, collectively—musicians and listeners—can say, “Oh, yeah…that feels right.”

But how exactly do the musicians play with each other to create this swinging sensation? This is what Theo Geisel wanted to find out.

swing physics

Geisel is a theoretical physicist with the Max Planck Institute for Dynamics and Self-Organization and the University of Göttingen in Germany. He’s spent decades studying the physics of synchronization — for example, how the billions of neurons in your brain coordinate with each other. He is also an avid amateur saxophonist. He even has a band with other physicists. (They play at conferences).

Geisel is now retired. This gave him more time to use his theoretical physics toolkit to explore other mysteries of the universe, including this one: How do musicians sync up when they try to create jazz?

“It’s a general belief that musicians should sync up as much as possible when they’re playing together. That’s true, of course, to an extent,” says Geisel.

But since the 1980s, some scholars and musicologists have claimed that the swing feel is actually created by small timing deviations between different musicians playing different types of instruments. To test this theory, Geisel and his colleagues took jazz recordings and used a computer to manipulate the soloist’s timing in relation to the rhythm section.

“We had experts—professional and semi-professional jazz musicians—assess how swaying these different versions of a melody are,” he explains.

The song they tinkered with was a recording of “Gordo,” a jazz standard written by Duke Jordan. In one version, for example, the pianist solo started at exactly the same time as the rhythm section. In another version, the downbeat soloist’s beats started the smallest part of the rhythm section, but their offbeat beats weren’t delayed.

Here’s what these two versions look like:

Did you hear a difference between the syllables? All is well. Most people probably wouldn’t, Geisel says. After all, the timing delay we’re talking about is minuscule – only 30 milliseconds, or a fraction of the time it takes to blink an eye.

However, the jazz musicians who rated the clips picked it up.

“They notice a difference and they can feel the difference,” says Geisel. “They told us they could hear the friction between the rhythm section and the soloist, but were amazed that they couldn’t say exactly what was going on.”

Geisel says expert musicians were about 7.5 times more likely to rate a version with pessimistic delays as having a more satisfying feel on the swing.

In another part of the experiment, the researchers also analyzed a database of more than 450 recordings by jazz soloists, including performances by the likes of Dizzy Gillespie, Joshua Redman and Charlie Parker. They found that almost all of them were using downbeat small delays for the rhythm section. “There were very few exceptions,” says Geisel.

He says these minuscule timing delays are not random. They are arrangers, although musicians probably do so intuitively.

So have scientists finally solved the swing code?

“We parsed a lot of it,” says Geisel. But he says there are some mysteries in individual art that science may never be able to solve.


Jazz musicians are searching for the secret of swingAnd McBride’s advice is: Study the greats.

“There’s a spiritual answer and then there’s a scientific answer,” McBride says. “You just have to listen to the people who’ve done it well. Louis Armstrong, start there. If you really want to hear someone who can swing, Nicholas Payton won’t be off to a bad start. Branford Marsalis won’t be off to a bad start either.”

Listen carefully, he says, and eventually the secrets of rhythm and timing will reveal themselves.

This story is part of our regular science series Finding Time – A Journey Through the Fourth Dimension to Find Out What Makes Us Stand Up.

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