The beguiling combination of kd lang's androgynous looks and sensuous voice propelled her to fame in the 90s but, asks Emine Saner, does she want her first collection of new songs in eight years to put her back at the top of the charts?

For a while, in the 90s, it felt as if kd lang was everywhere. Then she was nowhere. Today, she's here, in a hotel room in Cologne, halfway through a European tour of her first album of original songs in eight years. Gone are the model groupies, celebrity friends and media circus. She is older, wiser, more settled. A reincarnation, if you like.

She talks in slow, careful sentences with lots of pauses. With some people, this can feel awkward, but with lang it feels still, calming. I'm not sure if she's finished a thought, so I wait and watch her instead. She has filled out, like a middle-aged man with a wife who likes to look after him. She sits, cross-legged, on the sofa in her hotel room. Her face is fascinating; the slant to her eyes hint at a heritage that includes Icelandic and Native American, and when she smiles she looks beautiful. Her hair, greying now, is in the same style she had when her career started 25 years ago. "I cut it myself and I only know how to do one thing. It's not a fashion statement, it's just a result of inadequacy," she says with a laugh.

She is 47 and seems completely at ease with herself. She talks about getting older - "I love it. I feel happier and more content with what I have and who I am, and less - what's the word? Covetous. The older I get, the more I embrace who I am" - and how she can slip through the world almost unnoticed these days. "My public image is so low-key, but I get to travel the world and still have an audience and it's really amazing," she says. "I don't take that for granted."

We talk about why so few older women musicians are as revered as their male peers. "I don't know, there's some sort of disregard for women's perspective after a while. Music and the business of music is so sexually driven ... It depends, I guess, on how you were perceived. When women make their image about youth and sexuality, and not about intellect, that's kind of a dead-end road. So I think it's a combination of self-entrapment and entrapment by society."

Lang's longevity was never really in question. First and always foremost, there was her voice, as pure and wide and open as Canadian skies. She has also wriggled free of attempts to pigeonhole her and the simple fact of her masculine image seems to automatically afford her more respect. It would be pointless to bitch about lang losing her looks - as just about every other female musician over 40 has to endure - because she never played that game in the first place.

"I've always had an interesting relationship with my androgyny," she says. "It's kind of breadfruit - it looks poisonous but it's really good once you figure out how to get into it. I think the combination of my voice and my look was pre-ordained." It has often been remarked on, this contrast between one of the most sensual rich voices, one that can floor you with emotion, coming from a woman with a practical haircut and a wardrobe of shapeless suits.

Every day, she says, she gets mistaken for a man. "I like that," she says. "I didn't always, it bugged me sometimes, but I like going through the world kind of ambiguous. I definitely get less harassment, less attention." She means sexual harassment, not the attention that comes with being famous, which, as far as I can tell, she doesn't get much of any more, to her relief. "I remember one time I wore a really tight T-shirt that showed cleavage and some guy looked at my boobs and I was like, 'what?!' It was, to me, really crazy. It felt so alien. Being androgynous changes the sexual playing field too, because a lot of gay guys flirt with me, a lot of straight women flirt with me." She pauses. "Or they have - not any more, nobody flirts with me any more."

Lang was five when she realised she was gay ("I remember taking swimming lessons and being completely enamoured with Christy, the swimming instructor"), 13 when she came out to herself, 17 when she came out to her mother and 30 when she came out to the world. It's easy to forget now what an impact announcing you were gay had back then. There was some pressure from her record company not to, but looking back, she says, coming out both helped and hindered her. "I don't think [my album] Ingenue would have been a hit without me coming out, I wouldn't have got on the cover of Vanity Fair [in a barber's chair being shaved by supermodel Cindy Crawford]. But at the same time, I'm different."

At the moment, Katy Perry is at the top of the Billboard charts in the US with her song I Kissed a Girl (the former Christian rock poppet's previous song Ur So Gay was attacked for being homophobic). Doesn't it infuriate her when straight women pretend to be gay for publicity, for titillation? "The Britney-Madonna kiss [at the MTV music awards in 2003] annoyed me. I don't know much about Katy Perry, but I think there needs to be some inning now and then." She laughs. "Ultimately though, it's all good to play with sexuality and not be the gayest gay and not be the straightest straight. Ultimately, we're all bisexual, honestly I think that's true. I think [the gay community's] fears and expectations are the things that get all flustered when someone like Katy Perry has a song."

Katherine Dawn Lang grew up in Consort, Alberta, a Canadian prairie town, the youngest of four. Her mother was a teacher and her father ran the local drugstore. When she was 12, her father left for another woman and, apart from a chance encounter when she was an adult, lang never saw him again (he died last year and neither lang, nor her siblings, went to his funeral). She bristles when I mention her father, but she appears to have made peace with him.

After winning a singing competition as a child, lang knew this was where her future lay and all but gave up on school. She spent the 80s singing country, although by the time lang came out in 1992 (not only as gay but also as vegetarian, fronting an animal rights campaign), the affair with Nashville was over. She switched to torch songs, moved to LA to be near a married woman she had fallen for and channelled that unrequited love into Ingenue. There and then, lang exploded.

She describes the height of her fame as "really exciting but it was a fuck-up too. You can think you have the capacity to deal with it but nothing prepares you for it. I really thought I didn't care, that I could be famous and not be altered by it - but you are. You get caught up in it and some of it is real but for the most part, it's superficial and very fragile or temporary." Lang was everywhere and everyone wanted a part of this thrillingly different creature. What was it like to have Madonna coming on to her? "She never came on to me, that was a lot of publicity because we had the same publicist and it helped Madonna and it helped me," she says. "I don't think Madonna ever really liked me, to be honest. We're very different people." The trappings of fame and success became a diversion. "I had designers throwing clothes at me and then you realise you have to go to the fashion shows. Which seems very fun and good, until you realise you're in this kind of prostitutal exchange ... I woke up and thought, 'this is ridiculous'."

Lang had been touring Ingenue for a long 18 months and was getting tired and disillusioned. "I was starting to wake up to the 'nothing is free' perspective," she says. "I felt like there were all these expectations on me - from my manager, from the gay community, from myself." Her next album, All You Can Eat, was she says, "like the food at a buffet - total carbohydrates and no nutritional value. It sold, like, 38 copies and it was perfect because it did what I wanted it to do, which was snap me out of it."

She took herself off, started learning about Buddhism, met her partner, Jamie, a fellow student and settled down in her modest wood cabin in LA with their dogs. She released Hymns of the 49th Parallel in 2004, a simple, beautiful album of songs by Canadian songwriters including Joni Mitchell, Neil Young and Leonard Cohen, partly because she didn't know what else to do in response to the path America had taken after 9/11. "All the flags and the aggression and the throwing the stones back. The oppressive environment of fear. For a long time, I didn't know what to write or I didn't feel I had the capacity to say anything about it."

Lang allowed herself the time to let her new album, Watershed, develop alongside the changes that were happening in her that came with Buddhism. Where once her songs of regret and longing might have been tortured and melancholic, they are now pared-down and introspective. "I think I have a better sense of my weaknesses - being self-important, selfish and having a big ego probably triggers all the other stuff. I can see myself more clearly." Several of the songs are straightforward love songs ("I have slept there in the snow with others/Yet loved no others before") and lang's intense, youthful infatuation has given way to comfortable contentment. Is it important for her to be in a relationship? "No, but it's definitely a nice bonus. Life is so impermanent that it's not about somebody else or things around me, it's about knowing you are completely alone in this world and being content inside"

· Watershed is out now on Nonesuch records. kd lang begins her UK tour in Oxford on July 23. kdlang.com