The Grammy-nominated pop composer, Kara DioGuardi, will join veteran "Idol" judges Simon Cowell, Paula Abdul and Randy Jackson for the upcoming eighth season of U.S. television's most watched show when it returns in January 2009.

The addition of DioGuardi, 37, marks the biggest format change for the series, subtitled "The Search for a Superstar," since it burst into prime time on the Fox network in 2002.

Self-assured with a matter-of-fact, no-nonsense style, DioGuardi is expected to provide a counterweight to the sometimes gushy, even vacuous on-air persona of Abdul, 46, who first gained fame in the 1980s as a pop singer.

Though hardly a household name, DioGuardi has written and produced songs for numerous recording artists, including pop stars Gwen Stefani and Christina Aguilera as well as past "Idol" winners Carrie Underwood and Kelly Clarkson, and has received several awards in recent years.

In a conference call with reporters, she noted a previous collaboration with Abdul, saying they co-wrote a song early in her career, "Spinning Around," that went on to become a hit for Kylie Minogue.

"For the past seven seasons, Paula has had to endure the experience of being the only woman at the judges table," said Mike Darnell, head of alternative programming at Fox. "With Kara by her side, Paula finally has some back-up, and now there is going to be a lot more 'girl power' on the show."

Producers will put that chemistry to its first test on Tuesday, when DioGuardi joins Abdul, Cowell and Jackson for the kickoff of auditions in New York.

DioGuardi declined to critique her soon-to-be peers but said she finds Cowell, known for giving the most unvarnished appraisals among the panelists, to be generally fair. "I think Simon is pretty spot on most of the time," she said.

The record producer and talent scout described herself as "pretty feisty" and willing to stand up for her opinions.

"I'm going to be a straight-shooter," she said. "I'm just somebody who's really honest and gives my opinion, and if I feel the need to be hard with someone in order to get that across, I will be. And if I feel I need to be softer and more nurturing with some of the contestants, I'll be that."

The most important quality she is looking for in singers, aside from a "great voice," is a style that sets them apart.

"It's not about vocal acrobatics. It's about being unique and doing things that are identifiable to you," she said. "What makes an artist is ... when their song comes on the radio, I know exactly who it is."

She said her favorite song is John Lennon's "Imagine," a tune that figured prominently in the show last season as the signature performance of young crooner David Archuleta, who was narrowly defeated by rocker David Cook in the end.

The show averaged 28.1 million viewers weekly last season, compared to 30.8 million at the height of its popularity in 2006. But the finale in May between Cook and Archuleta drew some 32 million viewers, up 3 percent from a year earlier.

Although "Idol" has featured a three-judge panel since its inception, the program was originally conceived as having four panelists, said executive producer Cecile Frot-Coutaz.

Producers hired hip-hop radio personality Angie Martinez as a fourth member of the team for the second season, but she quit after judging a few auditions because she felt bad about having to reject some contestants and never appeared on the show.

Including the original British version, "Pop Idol," all had four judges.

DioGuardi is not a complete newcomer to TV talent shows, having served as a judge herself for ABC's short-lived, singing contest, "The One: Making a Music Star."