Classical music: old, staid, predictable, safe. Tango music: the opposite. Violinist Fionnuala Hunt talks to Arminta Wallace about finding common ground.

Fionnuala Hunt's new album, Tangos and Dances, is a delightfully tongue-in-cheek look at the history and context of tango music. Put it on, and I guarantee you'll find yourself doing a quick shimmy around the floor during the course of its sinuous 60-minute programme. But has Hunt herself ever danced a tango?

"No," comes the somewhat mournful reply, "but I'd love to learn. I brought two tango dancers to the launch of the CD, and it was unbelievable. It was the sexiest thing I'd ever seen in my life. And these two teach tango on Thursday nights - so I'm thinking about it!"

How, then, did a classically-trained violinist end up arranging and recording a tango album? Hunt says she came to it through the instrumental music of Astor Piazzolla, which has been popping up just about everywhere over the past decade, whether it be in classical programmes, world music gigs or simply on the radio.

"I got interested in what had influenced him, and where it all started, and what has happened to the music since his death in 1992," she says. "So I thought it would be fun to put together an album that charts the history from the 1900s right up to the present day, spanning the origins of the genre, the era of tango songs, and then the avant-garde, which would be Piazzolla. There is also music by three living composers on the album."

Four, actually. It obviously doesn't occur to Hunt to include herself - even though she did all the arrangements and the final piece on the album, Fino Irish Tango, is her own composition. It has taken her three years to complete this album, and it has clearly been an exhilarating learning curve - though there is, she insists, still plenty to learn.

"I don't think I even realised the significance of tango argentino until I saw those two dancers the other day. It's totally different to ballroom dancing tango, which most people will be familiar with. I thought the pace was much faster. But it's incredibly slow-moving; and, you know, she leans on him and he sort of drags her round the place . . . "

It is, in short, what George Bernard Shaw grumpily described as "the vertical expression of a horizontal desire". Bit risqué, all this amorous carry-on - isn't it - for a classical musician? Hunt hoots with laughter.

"It's absolutely startling," she agrees, adding, after a moment, "I'm trying to think of some way that I can introduce the dance into my concerts as well. But - and I have a bit of a bee in my bonnet about this - I do feel that, as classical musicians, we have a certain responsibility. We need to take into consideration that we've got dwindling audiences out there."

This was brought home to her with some force, she says, when she worked with the English violinist Nigel Kennedy a couple of years ago.

"I could see that the type of audience which went to his concerts was completely different to the usual classical audience. There were a lot of young people. Whether you like him or loathe him, he has managed to cross that barrier."

The audience at the first of her "tango" gigs at the National Concert Hall in Dublin last week, she says, was similarly diverse.

"There were a lot of people at that concert who wouldn't normally go to hear me play at all - and this is what I really hoped for. Because you can bring people in through the tango, and then play something like The Four Seasons as well."

It is, in many ways, a touchy subject. The history of classical music is littered with the skeletons of well-meaning attempts at crossing barriers. People do, however, respond to music-making that is genuinely creative - and Hunt's enthusiasm for tango, combined with the effortless virtuosity of her playing, is nothing if not infectious.

Into the bargain she is accompanied, on the CD, by the RTÉ Concert Orchestra - a versatile group of musicians who are well used to genre-bending musical outings of all kinds.

And tango music itself, as Hunt explains, is the product of a lengthy process of musical mixing and matching. "It has very dodgy roots. The dance came out of the suburbs and the slums of Buenos Aires. Then, in about 1907, several tango musicians went to Paris - which was the place to record music in those days, with all the best equipment and so on - and suddenly it became enormously popular in London and New York. Then it came back to Buenos Aires, and was accepted by all social classes."

It was the multicultural underbelly of Argentinian society which gave tango its extraordinary flamboyance. In the last two decades of the 19th century, Argentina was a major destination for many European emigrants.

"Because of all the exports of beef and grain, a lot of Europeans saw it as the land of opportunity," says Hunt. "People emigrated en masse from Italy and Spain - and of course they had a huge impact on indigenous music and dance. If you listen to a tango singer - Carlos Gardel, for instance - it's enormously dramatic. It sounds like Italian opera. You can hear at once that the Italian emigrants really had an impact."

Gardel was actually born in France, though he is revered as a national hero in Argentina. Add the influence of the Spanish population and the dance traditions of indigenous Pampas tribes, and you end up with the unmistakeable cross-rhythm of tango.

But there's tango - and there's tango. In the 21st century the form appears to be taking on a life of its own, developing in surprising and unpredictable ways - much as jazz once did. This diversity is reflected in the tracks on Tangos and Dances, which range from arrangements of Gardel songs through pieces by Ginastera and Albeniz to the most famous tango of them all, La Cumparsita.

You may not recognise the name. You almost certainly won't recognise the name of the composer - Gerardo Hernan Matos Rodriguez - and you probably don't know that it was written in 1917 as a marching song for the student federation to which the young Rodriguez (who was Uruguayan, not Argentinian) belonged. But close your eyes, conjure up two people dancing a tango, and it's almost certain that the accompanying melody will be that of La Cumparsita. Hunt's version is featherlight and cheeky rather than slick and sleazy, and uses special orchestral effects to give the music an authentic touch.

"Obviously I'm not authentic, because I'm not Argentinian," she says. "But I wanted to figure out some ways of getting the music to 'feel' right. This is the first time I've ever done any arranging on this sort of scale. I really enjoyed it - but it drove me mad as well. I go for a walk every morning, and on all those walks I'd think about the things that weren't working with the music and then come back and try to fix them. It was infuriating, but very, very rewarding."

So is she all tangoed out now? "No, no. I'm still crazy about it," she says. "Although I want to do a little bit of work with Irish traditional musicians as well. The tango project has brought this out, I think. I see a whole other side to me that I want to develop. Without losing the classical side of things, of course. I'm experimenting. We'll just have to see how it works."

• Tangos and Dances is on Avie Records. Fionnuala Hunt will play tango - and Vivaldi's concerto The Four Seasons - with the National Concert Orchestra at the Holy Redeemer Church in Bray on Friday and at Mullingar Arts Centre on Oct 21