Chat show host Ellen DeGeneres has been unveiled as the fourth judge on American Idol.

DeGeneres, 51, replaces Paula Abdul, who quit the programme before the start of the eight and current season.

The popular chat show host said that, although she lacked a musical background, she hoped she could become the voice of the viewer.

"Hopefully, I'm the people's point of view because I'm just like you," she said. "I'm not looking at it in a critical way, from the producer's mind.

"I'm looking at it as a person who is going to buy the music and is going to relate to that person."

DeGeneres will join fellow judges Simon Cowell, Kara DioGuardi and Randy Jackson at the start of the ninth series.

But her appointment has been met by criticism from fans of the programme.

Idol blogger MJ Santilli said: "I mean, really? Ellen DeGeneres? She guest judged 'So You Think You Can Dance' last season, and her critiques were comic relief.

“So is she going to be a real judge or some kind of joke? She's a comedian, not a singer or a musician. I'm kinda flummoxed here."