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‘Baby Driver’ Sound: Watch How Police Sirens Are Mixed to Jam With Jon Spencer Blues Explosion

Edgar Wright's longtime sound designer Julian Slater breaks down how sound works with music in the film's opening action scene.

“Baby Driver”

When Edgar Wright wrote “Baby Driver,” his car chase musical action film, he scripted the film’s big action set pieces to a handful of songs, but he was also thinking about the film’s sound design. So much so that he had an iPad app made where actors and studio executives could listen to the songs mixed by DJ Osymyso with key sound effects (footsteps, wiper blades, gun shots) while reading the film’s screenplay.

“Edgar writes with the sound in mind, but with ‘Baby Driver’ it is one of the characters,” said Wright’s longtime sound designer Julian Slater, who has been nominated for Best Editing and Mixing for his work on “Baby Driver.” “Baby [Ansel Elgort] suffers from his hearing problem, which is why he listens to the music. He’s in every scene and the idea with the sound design was to emphasize what he was experiencing. His tinnitus gets louder as he gets stressed, we remove the music from the left side of the theater when he takes out his left earbud, everything we did was to allow the audience to experience the film from Baby’s perspective.”

Entering Baby’s subjectivity through sound also meant the sound design would reflect the film’s narrative arc. In the first high-speed car chase, set to Jon Spencer Blues Explosion’s “Bellbottoms,” everything was going according to plan for talented getaway driver. That meant that Slater would need the sound effects to be in harmony with the song.

Ansel Elgort and director Edgar Wright on the set of TriStar Pictures' BABY DRIVER.

Edgar Wright reviewing a shot with Ansel Elgort


“We designed that first chase to be a bit more stylized and pitched perfectly with the music,” said Slater. “The choreography and the syncopation and the pitch correlation works according to how things are for Baby.”

For example, all the police sirens would need to be in tune and sync up with “Bellbottoms.” The challenge was the song doesn’t have a constant tempo, and a sound effect that worked for 10 seconds in one section of the song would be discordant ten seconds later.

“It’s a band jamming and the tempo goes all over the place and a siren that was working could quickly sound ridiculous or not realistic,” said Slater. “The challenge is when you hear it in the mix so that it’s working both musically and cinematically. It’s a constant trial and error. For every one that works, there’s were 50 that didn’t, and the trick is to keep all these audio balls in the air so it doesn’t grate on the audience, or become a tiresome device.”

For each sound effect he tried, Slater would “time squash” or “time expand” it so it fits musically at a particular point of the song, then adjust the pitch, and decide if works after listening to it.

“There’s five different sirens that we used in that scene,” said Slater. “We used all five and then in the mix we choose which is working best at that particular moment. So a New York siren that’s abrasive will work at particular moment with Jon Spencer, but 15 seconds down the line the frequency won’t work with the song. Each sound has its own sweet spot at particular moment in the mix and that’s when you are hearing it and we bury it when it’s not.”

According to Slater, the trick is to make the sound effect work musically, but not disappear into the song, as it would still serve an important purpose to heightening the scene’s conflict. The mix becomes about finding that balance, and if it’s a sound effect that needs too much volume to register with the audience, it’s not the right sound effect.

Later, as things don’t fall into place for Baby, Slater would find a different balance between music and sound effect. “In the next [action scene], where things start to unravel, and not go according to plan, then it’s less stylized and we are de-tuning the sounds,” said Slater.

Slater made this video for IndieWire to demonstrate how he mixed the sirens with “Bellbottoms.”

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