Women of heart: the seven Australian singers who will perform at the Opera House on Friday. Photo: Pat Scala

For seven female singers, the answer is simple: Joni Mitchell. They are avatars of adoration, who also have an asset the legion of Mitchell fans do not have: the musical ability to translate paeans of praise into performance.

The seven are Wendy Matthews, Katie Noonan, Rachel Gaudry, Louise Perryman, Kristin Berardi, Tania Bowra and Virna Sanzone. Backed by a 12-piece band, they will perform Joni - A Tribute to the Legendary Joni Mitchell at the Sydney Opera House on Friday.

Unlike her contemporaries, Bob Dylan, Neil Young and Leonard Cohen, Mitchell no longer tours. She last performed in Australia in 1983, when she was 39. Anyone holding his or her breath for a return visit may well have passed from blue to away. Her last tour in the US was nine years ago, and then to only about a dozen cities.

The void has been filled by tributes, performed and recorded. Two recent homages have been River: The Joni Letters, interpreted by Herbie Hancock and featuring Norah Jones, Tina Turner and Corinne Bailey Rae, and A Tribute to Joni Mitchell featuring James Taylor, Bjork, Cassandra Wilson, Prince and Emmylou Harris.

Friday's concert serves not only as a tribute but a surrogates' soiree of her work, in effect. All speak of her inspirational quality.

Rachel Gaudry, who is also the show's musical director, says the concert works chronologically through Mitchell's catalogue from the first acoustic albums through the jazz-infused phase, the '80s synthesiser-rock stage up to her orchestral reworking of her songs this decade. "From Court and Spark [1974] everything starts to get more electrified, and there's fairly complex arrangements," Gaudry says. "It's such challenging music, it's something you can get your teeth into."

Mitchell's music flows through Wendy Matthews's veins. She grew up in Canada with young parents in a house full of music. "Mitchell featured heavily on the family turntable," she says.

She also admires the songwriter's strength of character. "She is a person who held on to her integrity, unlike anybody else in the business."

Softening this iron in the soul are the flowers of poetry. "She is an incredible poet. She has an amazing way of putting universal feelings into very few words and have everyone know what she's talking about."

Matthews covered one of Mitchell's songs, Cherokee Louise, on her latest album, She. There is a personal reason for this. "Being a Canadian I grew up with a lot of native Canadian kids [she learnt recently there is native Canadian lineage in her background] and I could truly relate to that song."

Unlike many Mitchell admirers, Matthews favours the latter period. "I love the lower timbre in her older age where she's smoking five packets of Marlboro a day."

Matthews has been in the music business for 30 years, working with musicians such as Jimmy Barnes, Glenn Shorrock, Tim Finn and Kate Ceberano and, in the process, picking up seven ARIA awards. But she admits to nervousness about this show, in that it will involve performing the songs of a hero: "It's a huge call for me." She has, however, met Mitchell when she was living in Los Angeles. "She was incredibly quiet and shy."

Katie Noonan, in comparison, came to Mitchell quite late. "I was on tour with [my band] george 'round about 2001 and I was introduced to Joni by fellow muso Cindy Ryan. She asked me if I knew Joni Mitchell. I knew who she was, but I didn't have a record so she gave me Blue. I heard it and I was blown away by her writing, her voice, her lyrics and her phrasing. To be making music of that standard that young is just genius."

Noonan is now a "diehard fan. I've pretty much got all her records."

The tribute was a "gift and a challenge", she says. "You need to make it [the song] your own and they're often hard to sing - she had such a huge range in her early days, before her smoking."

The concert aims to evoke the spirit of Mitchell but "hopefully we can make it our own, that's the most important thing for me, and that's what she would want".

Through such tributaries, the river of song keeps flowing.

Joni - A Tribute to the Legendary Joni Mitchell is at the Sydney Opera House on Friday.