Children in Rutherford County have been arrested and jailed at rates unparalleled in the state. We’re investigating how that happened — and other ways the justice system there singles out children.

The Serial podcast series “The Kids of Rutherford County” begins with a hum. It’s a low hum, sort of ominous, that lasts for two or three seconds before the podcast’s host, Meribah Knight, comes in with, “It was a March afternoon in Rutherford County, Tennessee …”

The hum is a bass note, a low F, the lowest note J.R. Kaufman can play on his accordion in the Los Angeles home-slash-studio he shares with his half-brother and bandmate Justin Rubenstein. Once Knight begins speaking, Kaufman’s note slips beneath her voice, still there, but in the background.

The stories investigative reporters tell have drama. They have tension and tragedy, a natural fit for orchestration. (See, for example, “The Night Doctrine,” an animated film from ProPublica with music by Afghan composer Milad Yousufi.) Words and instruments work in tandem, as evidenced by the opening of “The Kids of Rutherford County.”

That March afternoon, Knight says, school was out for the day, “and a dozen or so little kids were playing a game of pickup basketball in someone’s backyard.” An upright bass comes in, doubled with Moog synthesizer, making four low thumps. “And then, as kids do, one said something about another kid’s mom,” Knight says. A Juno synthesizer runs through a bunch of guitar pedals, and then a high, oscillating melody arrives, from flutes and clarinets. The insult leads to shoving, Knight says, and shoving leads to a couple of feeble punches. Enter trumpet, harp and electric bass, all still in the background, kind of hidden, the music swirling, in step with the story.

Knight introduces the series, “This is ‘The Kids of Rutherford County,’” and as she finishes speaking, the music comes out of hiding; drums kick in, there’s guitar, a dash of pedal steel, and an explosion of trumpet, trombone and saxophone. It is here, for about 25 seconds, that the listener gets to appreciate the name of Rubenstein’s and Kaufman’s band — The Blasting Company — before the music slips back beneath the surface of the words.

This podcast series originated with a print story that Knight, a reporter at Nashville Public Radio, did in partnership with ProPublica. The story detailed how Rutherford County, southeast of Nashville, had illegally jailed hundreds, if not thousands, of children. After that story published in 2021, ProPublica and Nashville Public Radio partnered with Serial and The New York Times to produce a four-part podcast.

For ProPublica, partnering with Serial meant we got to watch colleagues do something we rarely do. We saw them set investigative reporting to music.

Between the two of them, Rubenstein and Kaufman play at least 22 different instruments on the podcast. Those instruments include the expected (violin, piano) and the less expected (pedal steel guitar). Rubenstein plays a lot of brass and strings, Kaufman a lot of woodwinds and keyboards. They also brought in five friends to play. Kaufman, asked to describe the podcast’s music, says, “I was calling it minimalist country classical synth music, and then Justin added, ‘with maximal tendencies.’”

In an Instagram post, Rubenstein and Kaufman joke that the music reflects their “super inclusive musical methodology: All instruments, everywhere, at all times.”

Rubenstein and Kaufman did not study music at a conservatory. Their education was more organic. Both played cello as kids, and it kind of rolled from there. “I basically learned the piano by not practicing cello,” Kaufman says. Rubenstein picked up the guitar because it was cool. As a young adult, Rubenstein, with a friend, bought a short school bus for $2,000, converted it to run on vegetable oil, and then moved into it with his brother. They lived on the bus while busking across the country, Kaufman on accordion, Rubenstein the trombone. The brothers formed The Blasting Company 15 years ago.

While Kaufman and Rubenstein are the composers, the conductor is Phoebe Wang, Serial’s senior sound designer and mixer. She finds the musicians and commissions the score, working with the musicians on the mood she’s looking for. Then she stitches and weaves the music throughout the story.

With “The Kids of Rutherford County,” Wang wanted the music to convey a sense of place. At the same time, “I didn’t want it to sound like a caricature of southern culture,” she says. She wanted music that isn’t too cleaned up or precious, that makes people feel something.

Wang found The Blasting Company courtesy of Spotify, when their hauntingly gorgeous song “Candy” popped up in her Discover Weekly mixtape. For Kaufman and Rubenstein, getting noticed in roundabout ways is kind of a thing. They got hired to score “Over the Garden Wall,” an animated miniseries on Cartoon Network, after one of the show’s writers heard them busking at the Hollywood Farmers Market. For this podcast, providing a sense of place would not be a reach. The two were born and raised in Nashville, next to Rutherford County.

Julie Snyder is Serial’s executive editor and its co-creator. She says that when scoring a podcast, she wants the music to help with comprehension most of all. These are long stories. There’s a lot of talking. Music can act like a cue for your brain. When music starts, you pay attention. When it stops, you pay attention. Music can be used in the same way that a section break is used in print.

With “The Kids of Rutherford County,” the score can be traced to a spirit of experimentation. On Zoom calls with Wang and Daniel Guillemette, a senior producer for Serial, the two musicians had woodwinds, horns, keyboards and whatnot scattered about, visible in their background. Rubenstein remembers the pair from Serial spying different instruments and saying, “Try that thing, try that.”

“We were game to try anything,” Rubenstein says.

In the end, Serial used close to 20 tracks that The Blasting Company created for the show.

Wang, asked to illustrate how she used particular tracks in the podcast, highlighted three:

Listen to “Mother’s Children”

“Mother’s Children” is the podcast’s theme song. It’s the track described at the top of this story and used in the beginning of the podcast’s first episode, as a childhood scrap blows up into something more. Wang calls it a “beautiful, ambient track” that is a slow burn. “It feels like it’s setting something up.” Since it moves slowly, she wanted it to deliver a real payoff — and that payoff is the blast that comes when Knight finishes her introduction. “It’s like the world is opening up to you,” Wang says of that moment.

For Kaufman and Rubenstein, that moment in the song is memorable because it’s the one time they were asked to go bigger. Most other times, with most other tracks, they were asked to be more restrained. But in this instance, as Wang kept requesting more, Rubenstein kept layering in trombones and trumpets while Kaufman added saxophones.

Listen to “Stone Door”

The “Stone Door” track — named for a hiking trail in Tennessee’s South Cumberland State Park, is threaded throughout the show. It was inspired by chamber music — a piece for a string quartet by Maurice Ravel, specifically — to which the composers added a clarinet section reminiscent of Tchaikovsky, then layered in electric guitar and rock drums. For Wang, this track provided “a feeling that something is off.” And that’s what The Blasting Company was going for. While scoring the podcast, Rubenstein says, “we’re thinking of the cognitive dissonance in the show, that things are always on the verge of falling apart.”

In Episode 1, the song starts within the first 10 minutes, as a child is writing down names for a police officer. (This will lead to all kinds of trouble.) In Episode 2, the track plays as a lawyer, flabbergasted at what’s before him, looks around a courtroom and thinks, “What the hell are you people doing?” In the third episode, the song comes in as Knight describes the tension between two realities: what the lawyers see (an illegal operation) and what the judge sees (a system with sound criteria). And in the final episode, the track appears one last time, as lawyers who have sued the county are driving around, searching, futilely, for potential plaintiffs who stand to be compensated, if only they can be found.

Listen to “Rites of Passage”

Kaufman remembers sitting on the floor, on a yoga mat as Rubenstein began playing a beautiful melody on the violin that would become “Rites of Passage.” It was “bendy” and “slidy,” Kaufman says. They added guitar, flute, other strings and drums, and sent it to Wang. Wang remembers listening to the song for the first time. “This is a special track,” she thought to herself. The strings were enveloping. Listening, she got a sense of place. She wound up using the track in a special spot at the end of Episode 1. The track plays as Knight describes how Rutherford County has been jailing a staggering number of children, so many that for the county’s kids, getting jailed was “almost a rite of passage.” The end of an episode is one of Wang’s favorite places for her favorite pieces of music, because the listener sits with the song. It’s a place for the music to shine.