Smog by name, smog by nature. Bill Callahan's music is a dark, dense, cloudy affair. He tells Sinead Gleeson that if it's not spiritual, it ain't music

IF YOU know anything about Smog, you'll know that the name is both fitting and misleading. Fitting, in that the music is dense, dark and nebulous; misleading in that most people (except fans) assume Smog is a band and not the moniker of just one man.

The man, Bill Callahan, is phlegmatic and known to be a man of few words. Like Will Oldham, he trades in that very American brand of world-weariness; the trailerpark troubadour. He's been performing as Smog for over a decade and, though he employs a band, Smog is still a solo project. So does he feel like a musical loner? "I don't really consider myself a solo performer, since I have worked with so many people."

With each album, from 1990's Sown to the Sky, Callahan constantly shuffles the line-up of musicians on his records. "I like to have a fresh start with each record, so it's like another chance, but I have considered trying to actually write songs from scratch with a partner. It's something I've been thinking a lot about lately."

Switching band personnel from album to album might be time-consuming and it's a wonder Callahan has time to write. However, his output verges on prolific - 2004 was the first year since he started releasing music that he didn't have either an album or EP out. After a two-year gap, Callahan has surfaced with a clutch of warm, pastoral tracks. He has always favoured the song-story, and on A River Ain't Too Much Love he deals in relationships, nature, death. Callahan thinks of songs as hymns. If there isn't any spirituality in music, there's no point to it, he believes.

"I believe that there are no words to relate divinity and that is what music is for. It can't help but be spiritual, I think, and if it's not, then it's not music, it's fashion or money or power."

A man who resists being bracketed, Callahan is distancing himself from his past work, trying to avoid being pigeon-holed with this album. There is a hint of light, of playfulness, about it. It won't get you pogoing around the room, and while it's distinct from his other albums, it recalls the best parts of Red Apple Falls and Knock Knock. Callahan's folk foghorn vocals have never sounded better and you can't help but hope that this album will bring him the wide acclaim he deserves. "I don't know how broad my audience is. I think the internet kind of ruined things because people know everything now, but just a little bit of it, nothing too deep," he says resolutely.

Callahan has a reputation for being a difficult interviewee, mainly due to his soft-spoken reticence, but for all the measured pauses he does possess a sense of humour. Discussing contemporary songwriters he likes, he is quick to pick one. "I like a lot of people, but I like R Kelly a lot. He's got a corner on something no one else does, which is really straight songs that are totally bent at the same time." I can't tell if he's serious or not.

Despite the opaque confessions of his songs, Callahan has said in the past that he "isn't interested in autobiography".

"The songs come from my eyes," he says. "That is, what my eyes see, which isn't really autobiography because I see so much more than my life, I see many lives."

So I have to ask if personal experiences are not what motivate him as a songwriter? "It's a drive; like I swallowed a stone some time back before my teen years and it won't dissolve in my stomach. It's just sitting in there every morning when I wake up and when I lie down in bed at night, the stone of songwriting is in my gut."

Smog play Whelan's, Dublin on Saturday, June 11th, The Limelight, Belfast on Sunday, June 12th and The Roisin Dubh, Galway on Monday, June 13th