Sia has been inescapable. For over two weeks that the Olympics ran, if you were within hearing distance of a television – for even under half an hour of time over that 16 day period of sporting achievement – you would have been exposed to her music. And, best of all according to the woman herself, you wouldn’t have even known it was her…unless you knew it was her song.

The opening eight musical bars – or thereabouts – of Breath Me have been on a seemingly endless loop as part of a commercial for supermarket giant Coles. “That’s why we said yes,” she confirms. “If it’s an ad, and they always check with me and tell me how much money they want to offer and if I think it won’t dilute my product then I say ‘yes’.

“I say ‘yes’ to a lot of places in Eastern Europe for yoghurt commercials,” Sia guffaws. “Coles was a tricky one for me. I don’t say ‘yes’ to commercials a lot, and certainly not in the territories where I sell records (or plan to) or where I come from,” says the Adelaide ex-pat, “and I know that the Australian politics in music is that there’s a lot of judgement and I wasn’t sure whether I wanted to open myself up to criticism by being called a sell-out.”

It’s become something like a calling card for Sia – from being brilliantly used in the final scenes of television series Six Feet Under to soundtracking this, that and the other commercial, it’s the song that’s made her who she is able to be today, financing not just the recording of new projects but the purchase of houses as well.

“Then I thought, ‘hahaha, what are you talking about – you did that LONG ago,’ and so I said ‘yes’ because it was enough money to buy a house. It was more than the Coca-Cola commercial that they used Breath Me in [in America], so I just had to say yes. I’m getting old. I want to be able to have kids, pay my mortgage, and take some time off when I have kids. I have to start saying yes,” she asserts, “because I don’t care so much about credibility now.”

It undoubtedly helps that Sia is a credible artist – after scoring her big break singing on the first few Zero 7 albums, her solo releases have gradually become more and more acclaimed as she’s continued to release them steadily but surely. In the early days of making music, Sia of course wanted to be the coolest cat in the kitchen. However, it’s as she’s embraced who she is as a person – and started having fun with her music – that she’s started making the sort of wildly idiosyncratic music that is a joy to listen to, such as the single Buttons a hidden cut on her new album Some People Have Real Problems.

“There’s some up-tempo stuff that I’ve never even put on albums, because I was told I wasn’t allowed to really, by a lot of advisors,” she explains. “They said that people want to hear the same down-tempo shit every album, and you’ll confuse the market, confuse the fans. If you listen to Buttons on this album it’s the direction that I’m going on – it’s hidden because it didn’t fit, we couldn’t sequence it anywhere else, it didn’t work. So we put it on the end because the video for that did a lot for me.”

The video in question was made by another Australian, Kris Moyes (the brother of The Presets’ Kim). It became a viral sensation, securing over half a million hits on YouTube after it had been uploaded to the internet. But, despite regularly writing with her bass player Ben Dixon, she doesn’t intend to team with any other artists anytime soon in any collaborative manner. “Just because I did the Zero 7 for a few years back everyone thought I was a collaborative artist, but I’m really not,” Sia affirms.

It took four years between her second solo album Colour the Small One and Some People Have Real Problems, but Sia is not planning on the gap between her third and her fourth albums being anything like as long. “I’m feeling in a much better mood and I want to make fun music that people can dance around to – it’s time to get jiggy,” Sia states, with tongue planted firmly in cheek. “Yeah. I said JIGGY. And now…I’m really embarrassed!”

The thing that’s often forgotten about Sia – particularly by those who only know her via down-tempo numbers such as Breathe Me – is that she’s very much imbued with the larrikin spirit of an Australian. She’s also got an Aussie’s work ethic; currently she has three projects on the boil. “I’m working on a new album, a musical which is primarily a musical project but which will be like a modern-day Annie, and I’m working on an animated pop project.”

With plans to tour in early 2009, Sia dashes away to work on her many, many ideas.

Some People Have Real Problems is out 11 October on Monkey Puzzle through Inertia.