Angelika Kirchschlager: This diva's got balls

Angelika Kirchschlager, bright and vivacious in jeans and a leather jacket, is anything but a traditional diva. But then, mezzos, forced by the prevalence of "trouser roles" into the shadow of glamourpuss sopranos, often have to be twice as good as their higher counterparts to get as far into the public eye; and Kirchschlager, about to star in Debussy's Symbolist masterpiece Pélléas et Mélisande at the Royal Opera House, used to be no exception.

Her voice is among the finest of its type, with a satiny texture, a glorious, light-catching gleam, bell-like precision and an ideal colouristic range illuminated by intuitive, perceptive intelligence. Her repertoire embraces everything from Handel and Mozart to Nicholas Maw's harrowing adaptation of William Styron's Sophie's Choice, which was premiered at Covent Garden in 2002.

It was the role of Sophie that propelled Kirchschlager towards international stardom. She once remarked that she suspected her career might be divided into "before Sophie" and "after Sophie"; several years on, she feels that's come true. "I think it's changed the way people perceive me," she explains. "Singing Sophie was a really strong statement that I'm a woman! I've been singing so many trouser roles - I still do. And it also proved that no matter whether I play a woman or a man, I can play somebody with depth. I think it added some dramatic colours that are important for the picture people have of me."

Trouser roles can provide meaty challenges and musical marvels - Mozart's Cherubino in Le nozze di Figaro, or Oktavian, the 17-year-old eponymous hero of Strauss's Der Rosenkavalier; and Kirchschlager is stunning as Sesto in Handel's Giulio Cesare in Glyndebourne's award-winning production by David McVicar, now available on DVD. But as Sophie, inevitably seen as stepping into Meryl Streep's shoes ("though I've never once watched the film," she remarks), Kirchschlager took everyone's breath away with the visceral, heart-rending power of her performance.

She seems likely to do so again with Debussy's Mélisande. Nothing in the heady and oppressive world of this opera is ever exactly as it seems. Based on Maurice Maeterlinck's play, it's filled with sensual wonders in which every word conceals layer upon layer of potential meaning. It's not inappropriate that Kirchschlager has nothing like the role's traditional interpretation up her leather sleeve. Instead of portraying the unlikely heroine as a fey, other-worldly mystery, she and the director, Stanislas Nordey, have discovered a heroine who is, in Kirchschlager's words, "emancipated beyond the world".

In the opera's shadowy, oppressive land, the king's grandson, Golaud, discovers the mysterious Mélisande weeping by a fountain, takes her home and marries her. She is drawn, however, to his younger brother, Pélléas, and the resulting love triangle gradually destroys all of them. Mélisande's past is hinted at but never revealed; as for the present, she often seems to have no control over her destiny. "What I like in our production is that it's a little bit turned upside down," says Kirchschlager. "She's not a weak woman who cannot defend herself. Stanislas Nordey sees her as a very strong person in the position of not being able to show and live her strength. It makes so much sense and I completely connect with this character. At this point of my life, doing this role is like a meditation for me. I feel so free in this production: she's always looking, listening, aware."

One of the most moving moments for Kirchschlager is the orchestral interlude after the jealous Golaud pushes Mélisande to the ground. "Then comes this huge music, this intensely painful drama; in our production she stands up again and faces her life, which is absolutely terrible. The music is full of hate, strength, desperation and decision, and just standing on this empty stage listening to it is an incredible experience. It's like a power point on a mountain where suddenly all the energy goes through you and you feel so safe and so strong."

Kirchschlager's musical power points are impressive to begin with. She was born in Salzburg and studied with the renowned baritone Walter Berry in Vienna, where she still lives. Sharing a dialect with Wolfgang Amadeus and a home city with the composer of some of the greatest songs ever written doesn't make her sing Mozart or Schubert better, she emphasises, but does affect her outlook: "It's amazing to know that I grew up with the same view as Mozart," she says. "He was looking at the same houses and hills, walking the same ways on the mountains, and we speak the same language. But this is just for my personal happiness - I don't think it has anything to do with making music. Other, more important things make a difference to that - and those are inside yourself."

Although she enjoys her operatic roles, her greatest love is for giving song recitals, with German lieder at their core: her repertoire stretches from Bach to Schubert to Korngold, plus a good dollop of French song and some favourites by Liszt. She's enjoyed duet partnerships with the baritones Thomas Quasthoff and Simon Keenlyside (her Pélléas at the ROH) and among the summer's highlights will be Kurt Weill's Seven Deadly Sins, with the Berlin Philharmonic under Rattle's direction, shortly after Pélléas.

What attracts her to lieder is the genre's core: the combination of poetry and music. "I love to think about what the composer did with a word, why did he stretch this one? That's fascinating in German lieder, because the word always comes first for the composer. You can compare the same poem set by sometimes four, five or six composers, and the difference is amazing. It tells you so much about the composer. You know how he thought about the poem's essence, what it meant to him.

"Now I have reached a stage where I just want to sing things that I really love to sing," she adds. "I don't want to fight any more. I've tried out a lot of things, I know what I can do, I know what I should not do, I want to pay more attention to my family and I feel my really strong side is recitals."

Knowing how best to expend valuable energy is certainly an essential quality for a thoroughly modern opera star, especially one who is a mother - Kirchschlager has an 11-year-old son. "In theory you can take a plane at 6am and be at a rehearsal at 10am, but that means you have to get up at 3am and you lose all your sleep," she says. "I used to do that, but I just don't any more. I'm so strict now. And on my son's birthday, I don't go anywhere. People have tried so hard to persuade me, but I say no. I want to be there when he wakes up at 7am and I want to be the first to say happy birthday, because that's what counts for him. He has to be the number one."

As for relaxation, she loves simply to be at home. "I like to go to the supermarket and decide what to cook. I invite friends round and we open some red wine and talk; and I love cleaning the apartment - I'm very good at throwing things out! And I love just to walk through Vienna - walking and looking. It's so beautiful."

'Pélléas et Mélisande', Royal Opera House, Covent Garden, London WC2 (020-7304 4000), 11 to 23 May