Listening to Lisa Gerrard and Pieter Bourke talk about the recording of the album Duality, it becomes clear that this project combines the strengths of both artists, and finds them communicating musically with clarity and precision. What's curious, then, is that this harmonious pairing occurred more by chance than design.

Early in 1997, Gerrard invited Bourke to her home studio in Australia to engineer and play percussion on a few new compositions. But after recording a couple of pieces, the two realized that a fruitful partnership was emerging. "We were collaborating more in the writing area," Gerrard says. "And it became very interesting to us because we discovered that most of the things that I am not good at, Pieter was, and most of the things he doesn't endeavor upon are my area. It was interesting to see how strong we were, because it was such a good match."

"I thought I'd be there working for maybe three weeks," says Bourke of the original plan. "And we spent a year doing it, working really, really intensely for that period of time."

What resulted is an album of luminous, tranquil and moving music. Created with voice, percussion, electronic keyboards and samplers, Duality is an organic marriage of sounds that Gerrard describes alternately as "classical" and "contemporary." "Classical because it's abstract in nature and is a unique journey for every individual, but contemporary because it's a mosaic of cultural influences and is the voice of what we've experienced in the past 20 years of our artisanship."

Gerrard and Bourke had worked together before, when Bourke played percussion on Gerrard's first solo album, The Mirror Pool, and on the 1995 world tour, and again a year later when he toured with Dead Can Dance -- the 20-year, nine-album alliance of Gerrard and musical partner Brendan Perry -- in support of the Spiritchaser album, their most recent release. Dead Can Dance has drawn fans and acclaim worldwide for their haunting, transcultural music, a music inspired by a wide range of ethnographic influences yet decidedly personal in nature, and they are recognized as originators of what is now generally called world beat.

Bourke, a songwriter, keyboardist, percussionist and remixer, was a member of the Australian band Eden from 1988 until 1993, when he began working with David Thrussell (Snog, Black Lung), first as Snog and then as Soma. On albums (Dear Valued Customer, Hollow Earth, The Inner Cinema), singles, remixes and an EP (the recent Stygian Vistas), Bourke and Thrussell have drawn on numerous elements -- trip-hop, drum 'n' bass, jazz, rock, techno, pop and dub among them -- to create electronic music that has been called "completely new," "timeless" and "a milestone of modern sonic sculpture."

Still, for all of Gerrard's and Bourke's enduring musical collaborations, the connection they discovered in the studio surprised even them. "The title of the song 'Nadir' is a Sanskrit word that means synchronicity," Gerrard says. "And it really depicts the celebrational concept of the whole process of what we did together. That's how we mean Duality, as synchronicity." The light, spirited composition offers an uplifting finale to a passionate, reflective album. "We were laughing so much when we were doing it," says Bourke. Adds Gerrard, smiling, "We had a ball making this record. It's true."

Setting the tone for this album of luminous, tranquil and moving music is "Shadow Magnet," the opening track. The low sound of a wind instrument floating on the air is joined by Gerrard's clear, rich voice and layers of string sounds. An insistent percussion groove then lays a foundation for the track, anchoring the ethereal calm of the wordless melody.

"Ultimately, in doing the work, you draw upon something that is the river of life that you possess," says Gerrard. "Music has a voice inside it that calls you, and you know that this is your work, this is what you must do. It doesn't differ, project by project -- that's the way you work. But the unique quality of this situation is that we were able to find such a gentle equilibrium, an unspoken common ground that allowed us to be liberated by what we were making and not ashamed, not afraid."

"I've never experienced the fluidity and the trust that existed between Lisa and me in this work," says Bourke. "So much was unspoken while we were working, but whatever idea came up, we would take it as far as we could, and that was something that was really magical. We tried to put aside the intellectual process, so we went out approaching the work in a state of innocence. I often felt like we were working on music for the first time, which is an amazing feeling to have after you've been making music for 15 years."

"Unfolding" is a corporeal example of that process. As a chordal progression is sung by a choir (actually 12 tracks of Gerrard's voice, sung live to tape, that create a choral wash) and then embellished with string parts, the composition seems to reveal itself, growing harmonically and emotionally. Then too, "Human Game," which begins with the sound of children (Gerrard's 5-year-old daughter and 10-year-old niece) laughing and playing, suggests the relaxed feeling of the studio. "The kids were straight outside the studio window, jumping on the trampoline, and we stuck the microphone outside and ran around and played chasey with them for awhile," says Gerrard. "It just brings such a positive energy." The words, the only English lyrics on the album, came "automatically," as all of Gerrard's do. "When we were through recording that song, Pieter and I had to sit back and listen to what the words were saying because it was the first time we'd heard them."

The rest of the vocals, sung with sounds rather than in a conventional language, are an example of melismatic singing. "It's a language invented within the music, inherently, and the words mean more than I can say in English," she says. "The way I sing is not new; it's been around since the beginning of time, and it's something all children are born with. It's not unique to me, but for some reason I never lost the ability."

The creation of the music on Duality came about in much the same way. "It was very much an unlocking process," says Gerrard. "We were working from minimalistic areas -- drones or a percussion piece or a vocal part -- and would build the lineal fragments upon that in a horizonal sense, in a landscape sense. We were working very much in a transcendental way, in order to allow the essential narrative of the work to reveal itself, and so each part that was applied transcended the original parts into another piece of music." "It's like the clave, in African music, the cowbell part that everything else is locked into," says Bourke. "When the clave changes, it sounds like everything has changed, but it's only the clave that has. That quality is what we were looking for in each new part that came up, whether it be a vocal, a keyboard line or an abstract sound, a bird sound or other natural sounds. If it transformed what was already there into something else, that's the thing we were looking for."

In composing their music, Gerrard and Bourke have created a deeply personal expression driven not by pop culture but by a myriad of cultural inspirations -- and each other. "We were always there working together, and the decisions were made together," Bourke says. "There was an unspoken agreement that we created between us that allowed that to happen. That's why it's called Duality, because we felt we worked as one, that our two personalities came together as one." "I think you can feel that essence in this project," says Gerrard. "I think people who are listening, with soul and ears, can just enjoy the music for what it is -- which is all we want to do at the end of the day. We just want to be able to enjoy it for what it is."