MARY LOUISE KELLY, HOST:
Now a mystery about music...
(SOUNDBITE OF LOUIS ARMSTRONG SONG, "WHAT IS THIS THING CALLED SWING?")
KELLY: ...Specifically about jazz.
(SOUNDBITE OF SONG, "WHAT IS THIS THING CALLED SWING?")
LOUIS ARMSTRONG: (Singing) What is this thing called swing? What is this thing called swing?
KELLY: In 1939, Louis Armstrong asked a question that musicians still debate. What creates the swing feel in jazz? Now physicists think they've got an answer, and it all has to do with the subtle nuances in timing. As part of our science series Finding Time, NPR's Maria Godoy has a story.
(SOUNDBITE OF SONG, "IT DON'T MEAN A THING (IF IT AIN'T GOT THAT SWING)")
ELLA FITZGERALD: (Singing) Don't mean a thing if it ain't got that swing. (Vocalizing).
MARIA GODOY, BYLINE: As Ella Fitzgerald and many others have sung, swing has long been considered an essential component of jazz. It's hard to put into words, but you might describe swing as a rhythmic phenomenon, a propulsive, groovy feeling created when performers are playing off each other in a way that makes you just want to move to music.
(SOUNDBITE OF ELLA FITZGERALD SONG, "IT DON'T MEAN A THING (IF IT AIN'T GOT THAT SWING)")
CHRISTIAN MCBRIDE: Swing is a feel. There's a certain language. There's a certain inflection of rhythm.
GODOY: Christian McBride is a Grammy-winning jazz bassist, music educator and host of NPR's Jazz Night In America. He says one defining component of swing is how eighth notes are played. Instead of playing them straight...
MCBRIDE: And that is like - (beatboxing).
GODOY: In jazz, these notes are swung, meaning the downbeat or every other eighth note is played just a little longer, while the offbeat notes in between are shortened, creating a galloping rhythm, like this.
MCBRIDE: (Imitating cymbal).
GODOY: But jazz musicians know that technique alone can't explain swing. After all, even a computer can swing a note.
MCBRIDE: A computer just ain't - it just ain't going to swing that hard, you know? You still don't get the real, proper swing feel, which is a human feel. You know what I mean?
(SOUNDBITE OF CHRISTIAN MCBRIDE AND INSIDE STRAIGHT'S "STICK AND MOVE")
GODOY: That's McBride swinging with one of his bands.
MCBRIDE: For me, I think you've got to lock people in and say, OK, here's where the time is. Here's where the rhythm is. And then everybody collectively, the musicians and the listeners, can go, ah, yeah, that feels right, right?
GODOY: But how exactly are musicians playing off each other to create that swing feel? That's what Theo Geisel wanted to find out.
THEO GEISEL: I'm a professor of theoretical physics.
GODOY: Geisel is director emeritus of the Max Planck Institute for Dynamics and Self-organization in Gottingen, Germany. He studies the physics of synchronization - for example, how the billions of neurons in your brain coordinate with each other. He's also a passionate amateur saxophonist. He even has a band with other physicists. They play at conferences. Over the years, Geisel has wondered...
GEISEL: How do musicians synchronize when they try to create swing in jazz?
GODOY: Now, you would think that musicians should synchronize as best they can when they play together.
GEISEL: This is true, of course, to some extent.
GODOY: But since the 1980s, some scientists and music scholars have claimed that the swing feel is actually created by minute timing deviations between different instruments. To test this theory, Geisel and his colleagues took jazz recordings and used a computer to manipulate the timing of the soloist with respect to the rhythm section.
GEISEL: We had experts, professional and semi-professional jazz musicians, rate how swinging these different versions of a tune were.
GODOY: In one version, for example, the piano soloist started at the exact same time as the rhythm section, like this.
(SOUNDBITE OF MUSIC)
GODOY: In another version, the soloist's downbeat started just the tiniest bit behind the rhythm section, but their offbeats were not delayed. That sounds like this.
(SOUNDBITE OF MUSIC)
GODOY: Didn't hear a difference between the clips? It's OK. Geisel says most people probably won't. After all, the timing delays we're talking about are minuscule, just 30 milliseconds or a fraction of the time it takes to blink an eye. Even so, the jazz musicians rating the clips picked up on it.
GEISEL: They noticed a difference, and they could feel the difference. They told us that they could hear a friction between the rhythm section and the soloist, but they were amazed that they could not identify what was going on exactly.
GODOY: Geisel says the expert musicians were 7 1/2 times more likely to rate the version with the downbeat delays as swinging harder. The researchers also analyzed over 450 recordings of jazz soloists, and they found that almost all of them were using tiny downbeat delays relative to the rhythm section.
GEISEL: There were very few exceptions.
GODOY: Geisel says these tiny timing delays aren't random. They're systematic. The musicians are probably just doing it intuitively. So have scientists finally cracked the code for swing?
GEISEL: Well, we have cracked a lot of it.
GODOY: But he says there are some mysteries of individual artistry that science might never be able to unravel. As for jazz musicians seeking the secret to swing, McBride says study the greats.
MCBRIDE: There's a spiritual answer, and then there's the - you know, the scientific answer. You know, I think you just got to listen to people who did it well. Louis Armstrong - start there, you know? You actually want to go hear somebody who can swing their butt off? Nicholas Payton would not be a bad start. Branford Marsalis would not be a bad start.
GODOY: He says listen closely, and eventually, those mysteries of rhythm and timing will reveal themselves. Maria Godoy, NPR News.
(SOUNDBITE OF LOUIS ARMSTRONG SONG, "WHAT IS THIS THING CALLED SWING?") Transcript provided by NPR, Copyright NPR.
