Barrington's Wild Belle looking forward to Lolla

The last time Natalie Bergman played a festival in Chicago, she almost collapsed. "I wore my ... leather pants, and it was like 500 degrees out," she says, laughing over the sole tidbit she remembers from her band Wild Belle's set at last summer's North Coast Music Festival.

Things are poised to be more memorable when the reggae rock group makes a hometown appearance at Lollapalooza on Sunday night. While the former Barrington resident is still a slave to style (she and brother/bandmate Elliot just starred in a Gap Styld.By campaign), Wild Belle looks forward to letting loose the first new music they've recorded since releasing their lauded Columbia Records debut "Isles" in 2013, which led to their first Lollapalooza gig that same year.

"It will be a whole new set," Bergman promises. One of the songs, she says, will be the premiere of the breezy dance pop hit "Be Together," that Wild Belle contributed to Diplo collaborator Major Lazer's 2015 album, "Peace Is the Mission." It has racked up more than three million views on YouTube to date. They will also unveil new tracks from their own anticipated sophomore release, which is coming "very soon," promises Bergman, much to the delight of the 80,000 Facebook followers who ask about it daily. While she is mum on the album name or official street date, the first single is slated for this fall, and Bergman hints at how much the band has matured for the new material.

"The sound overall now is little more rude and heavier," she says, calling it a definite evolution from "Isles," which produced hits like "Keep You" and "Happy Home" that combined rock steady, reggae, tropicalia and bossa nova into a neat indie pop package. "That first album I wrote when I was basically a teenager, so the songs are not as relevant to me. I still love them and love performing them but it's not the same place in my heart or mind or life right now."

At that time Elliot had just gone off to college and started his own Afrobeat jazz fusion band called NOMO, but before he left home he gave his younger sister a compilation tape full of Jamaican singers like Della Watson and Della Humphrey who had recorded at the country's famous Studio One.

"I was obsessed with it and wanted to know everything about that early rock steady style," says Bergman, who had been participating in her school's gospel choirs and began writing her own tracks. Elliot invited Natalie to try recording with NOMO.

"I basically stole his band," she laughs of the early days when the group was called The Rhunes; today, most of NOMO continues to play live with Wild Belle.

"It's been a wild experience. There have been a lot of ups and downs, that's for sure," she says, alluding to a theme of loss that admittedly permeates the new album. Though she's hesitant to elaborate, she admits, "I've spent a lot of tears and blood on this record."

To help hone in on the evolving sound, the Bergmans tapped into a new team of collaborators, including Patrick Carney of The Black Keys and The Weeknd producer Doc McKinney. They also found new creative spaces to record, starting out at Geejam Studios in Jamaica and later setting up camp at Natalie's new home in California.

While Elliot continued his experimentation of building instruments (his electric kalimbas are all over "Isles"), the younger Natalie took more authority this time around, adding more of her electric guitar flourishes, letting her surfing hobby seep into the beachy vibe of the music and even importing some of the revving and roaring sounds of her 1955 Mustang into certain songs. She's also started working with a choreographer to add dance to the live sets and upcoming music videos.

"We're ready and dying to share this new stuff with the world," says Bergman. And she's keen to start with Lollapalooza, a place she is most fond of for discovering Amy Winehouse at that famous set in 2007. "It's probably the best moment I've had at a festival," she says, perhaps speaking too soon.