By MELENA RYZIK

LOS ANGELES - “Barf!” Rihanna squealed, at the sight of a pair of pale pink satin Brian Atwood stilettos. In her world this is a compliment. “Usually it’s ‘ill’ or ‘I want to throw up on it,’ ” she explained. “But barf is the worst,” meaning the best. “Barf is 10 out of 10.”

In a simple rehearsal space near the Burbank airport, Rihanna, the R&B star, was picking out the most stunning outfits for her next few weeks of appearances.

The look for Rihanna’s performances was sexy-tough, the diva you don’t want to mess with; her lyrical slogan, she said, is “I’m such a freaking lady,” using the version without the curse word.

At the end of a pass through her set, she raised her arms in a fierce warrior pose and stuck out her tongue, a rare reminder that the phenom at the center of all this activity is just 21. “Rated R” is her fourth album, and in some ways her most risky, another step in the evolution of a persona that is, as the title of her multiplatinum 2007 album put it, “Good Girl Gone Bad.” It is also, she said, her most personal album, a response to her breakup with the singer Chris Brown, who assaulted her in a car in February after a pre- Grammy party.

Mr. Brown pleaded guilty to felony assault and received a sentence of five years’ probation, six months community labor and a year of domestic-violence counseling. Horrified by the attention the assault received, Rihanna retreated for months . But though she is somewhat reluctant to be a symbol for surviving domestic violence, she insists that the experience helped her make what she calls in her liner notes “the album of a lifetime,” to turn bad into good.

“As traumatic and as terrifying as it was,” she said, “and sometimes I wish it never happened, my whole life changed in the most amazing way after I went through that. If I didn’t go through that, I swear, you would’ve been interviewing a completely different person.”

It’s a strange time to be Robyn Rihanna Fenty. (Her close friends and family still call her Robyn.) “Good Girl Gone Bad” spawned numerous hit singles, including the dance-pop “Don’t Stop the Music” and the enduring “Umbrella,” a Grammy winner. Her taste for runway looks has made her a fashion-world favorite; she even has a name-brand haircut, the Rihanna, short with punky, skater-boy bangs. By 20, she had achieved the level of success she had often imagined while growing up in Saint Michael, Barbados, where she began performing living room concerts at 6. She left at 16 to begin a recording career in the United States.

“In the beginning, everything was a little more manufactured,” she said after rehearsal . “It had to be safe, and in order for it to be safe, it had to be done before, which made no sense to me.”

Gradually, she outmaneuvered the spunky teenage rep for something raunchier, darker and less conventional. That aesthetic is on full view on “Rated R,” which has more muscular beats, ominous lyrics and a bass-heavy sound that Rihanna described as “a lot more grimy.”

L. A. Reid, the chairman of Def Jam Records and an executive producer of the album, said Rihanna had always been confident in her own point of view. “She’s not looking to be a consensus builder, she’s not looking to see what the room thinks,” he said. “The people that work with Rihanna execute what she thinks.”

But when Rihanna entered the studio just two months after being beatne by Mr. Brown, she wasn’t prepared to get personal.

“It was exactly what I tried to stay away from,” she said. At the time she was not speaking, publicly or privately, about the assault. “Everyone wanted me to see a therapist to just talk about it, and I refused,” she said. “In Barbados we don’t do that. We keep it in our family, and figure it out and move on. I just put my game face on and went on with my life. But deep down inside I had some things to get past, and it came out in the music.”

Rihanna’s new album, ‘‘Rated R,’’ is a response to her breakup with Chris Brown. / FRED R. CONRAD/THE NEW YORK TIMES