Assume the position! Sing like a canary

It seems odd, sitting across from Joan Wasser, that for the first 30 years of her life it never occurred to her to open her mouth and sing. After just a few minutes in her company, during which her voice emerges as a conspiratorial murmur one moment, and an intense, throaty bellow the next, you really can't imagine her doing anything else.

Over the past five years, the 40-year-old singer-songwriter who goes by the name of Joan as Police Woman has carved a reputation as a peerless practitioner of indie-soul music. She has been called "Dusty Springfield for the indie generation", though she prefers to describe her music as "the sound of wind rushing through the forest".

She is, in person, a tornado of a woman, a sight to behold in leather jodhpurs, T-shirt and a fluffy white coat, and armed with a powerfully upbeat demeanour that belies that sadness and subtlety of her music.

Singing, Wasser insists, was not in the plan. "I never thought I could do it, and when I tried, it was terrifying. I was happy playing alongside other musicians. I was simply doing what I had been preparing all my life to do."

That musical life began when she took up the violin, aged eight. For years she pursued a classical path, landing a place at Boston University to study music under Yuri Mazurkevich, and playing with the Boston University Symphony Orchestra. But by the time she graduated, Wasser had become exasperated with academic life and "didn't want to play the same pieces that had been already been played for ever". So she sculpted her hair into a mohican and, armed with her violin, joined a series of "really, really loud" punk-rock bands with former members of the Flaming Lips, the Grifters, and Shudder to Think. Gradually, however, her sense of rebellion dissipated, and her penchant for punk gave way to a love of vintage soul by, among others, Isaac Hayes, Donny Hathaway and Al Green.

In 1994, she began dating the revered singer-songwriter Jeff Buckley, whose life was cut short three years later when he drowned in Wolf River, Tennessee. Shortly after, Wasser started playing music with Buckley's bandmates under the monicker Black Beetle. They had moderate success – there were support slots for Morrissey and Patti Smith – though for Wasser it was an unhappy time.

"We were all really struggling," she recalls. "It was a period when we were making music just to stay alive and be together and try to make sense of a situation that didn't make sense. I think it was as a method of coping that I started writing songs. It was hard but also incredible, and it propelled me forwards."

At the same time, Wasser was cultivating a sideline as a studio session musician, playing violin for such starry names as Elton John, Lou Reed and, later, Rufus Wainwright. Much of her time was spent watching and learning as well as playing. After the rigorous discipline of her college days, this was a musical education of an entirely different kind.

It was an encounter with Antony Hegarty, of Antony and the Johnsons – she was brought in for the day as a substitute violinist and then hired by Hegarty on the spot – that gave her the self-belief to go it alone. "He just blew my mind, and being around him was very inspiring," she says. "He became a great friend and really gave me courage."

Wasser tentatively began singing and gradually her confidence built. Black Beetle broke up in 2002, leaving Wasser with a pile of songs and the possibility of fronting her own band. With Hegarty's encouragement (he duetted with her on her first album), she took the plunge and formed Joan as Police Woman. The name was inspired by a Seventies TV show in which Angie Dickinson plays a tough, sexy LA cop. Oddly, Wasser doesn't own a television and hasn't for years. "Well, they don't play that show any more," she protests.

Word soon got around about her intense live performances and in 2004 Rufus Wainwright, with whom she'd already done studio sessions, asked her to support him on tour. In 2005, she signed a record deal and, a year later, released her first full-length album, Real Life.

For Wasser, music has been the medicine that has carried her through difficult times. Having emerged from the trauma of Buckley's death, Wasser later endured the suicide of her close friend Elliott Smith in 2003 and, four years later, the loss of her mother from cancer. In each case, she says, she fought the impulse to retreat alone with her grief, instead channelling her feelings into her songwriting.

Asked how she found the strength, she replies: "I think it goes back to being adopted as an infant. I had amazing parents but I was so very different from my mother that I would look at her and go 'Who are you?', and she would do the same with me. My brother and I always knew we were adopted and we had to learn to be very secure with who we were and not bury all that stuff in a box. Having all that happen to you makes you very resilient. It can also make you love life, whatever it throws at you."

Now Wasser is preparing for the release of her third album, The Deep Field, a captivating and characteristically soulful work named after a distant part of space. "I'm a little bit of a science geek, so when I learned about that idea, I found it very romantic," says Wasser.

Even with the many traumas that Wasser has been through, she says it is romance that underpins her work, a fact that is born out by the first single "The Magic", a piece of Seventies soul that could have been written by Curtis Mayfield. Elsewhere, the song "I Was Everyone" is written from the point of view of Joan of Arc and the experience of hearing a divine voice. "I'm named after her, so I always thought I might be burned alive before I was 20," says Wasser cheerfully.

Six years into her solo career, Wasser has also kept up the collaborations with fellow artists. She played violin on the Scissor Sisters' last two albums and provided vocals, violin and guitars on Lloyd Cole's latest offering Broken Record. Last February she joined Damon Albarn on a tour of Ethiopia as part of Africa Express, a project that brings together Western and African musicians.

"The practice of working with other musicians is pretty much the opposite of how I was trained when I was studying," Wasser says. "It's all about being with other people with no music in front of you, bouncing ideas off one another and just using your ears. It's about spontaneity and interchange, and you never stop learning. For me, that's a pretty cool way to make music."

'The Deep Field' is released on 24 Jan on Reveal. The single "The Magic" is out on 17 Jan

Helping police with their inquiries

Joan's collaborators

On Antony Hegarty..."After that first rehearsal we instantly clicked. His singing just killed me, and as a human being, he is just like his music: quiet, beautiful, otherworldly. He's very loving and he really helped me in my life in so many ways. I always say he's my spiritual guide. I actually think he's a real-life angel."

Rufus Wainwright..."I originally met him through Antony. He knew I played violin but he didn't know I could also play guitar and sing. Later, I opened for one of his tours and that really kicked my ass. He is really impressive when he's working. He knows exactly what he wants musically and he doesn't stop until he gets it. He's a proper classical singer. He taught me everything I know about singing."

On Damon Albarn..."He is one of my all-time heroes. His voice and his melodies just stay with you. I went on his Africa Express tour, and it was the most incredible experience I have ever had. We went to Ethiopia and saw the most off-the-wall bands in clubs. The Ethiopians were so open and interested in what we were doing, and their music had these time signatures which we have no real knowledge of. It was a revelation.