MUSIC: Now You Squeeze It; Purcell Room, SBC / Cabot Hall, Canary Wharf, London

The first accordionist I heard was Jimmy Shand. I hated the instrument. It domesticated the wildness of Scottish bagpipe music and, from junior school country dancing to The Archers' theme tune, that seemed to be the accordion's function. Yet the characteristics that appealed to Shand make the accordion one of the world's best-travelled instruments. It's a portable orchestra, assuming the coloration of whatever musical tradition takes it to heart. Nor need it sound Shand-bland: the wheezing, whining accordion and strangulated vocals of Cajun give voice to a culture cast adrift, holding on to life with desperate fervour, and while there are links between Cajun and "Scottish country dancing", the musics are now worlds apart.

The personable figure of Eddie LeJeune represents Cajun in the accordion festival "Now You Squeeze It", and, a mark of the instrument's universality, he's joined by players from three continents: South America, Europe and Africa. The festival opened on Wednesday with Regis Gizavo from Madagascar, whose style grafts Malagasy music on to Western rhythms; and Finland's Kimmo Pohjonen, whose playing brutally deconstructs the neutered folkishness represented by Jimmy Shand but apparent throughout Europe.

While Gizavo clearly loved the chance to bring his, and his country's, music to a new audience (this was his British debut, although he's lived in Paris throughout the 1990s), Pohjonen's act is minatory and threatening. He's as much performance artist as musician, which is not to suggest that his playing is unmusical. With the aid of a wah-wah pedal and some sophisticated electronic manipulation, he transforms his gleaming machine and, occasionally, his voice, building a dense aural fog in which sounds are simultaneously produced on-stage and mutated in electronic hyperspace. Pohjonen's instrument sighed and rustled, or barked like a dog and roared like a lion. If the results often sounded like heavy metal for accordion, Pohjonen's theatricality held the attention. At the show's climax, he seemed to be engaged in battle with his accordion, which threatened to exact revenge for indignities suffered by coiling itself around his muscular body and squeezing the life from it.

Regis Gizavo's relationship with his instrument is altogether more benign. His music has roots in the trances and rituals of Madagascar, but since coming to Europe he has formed a musical partnership with percussionist David Mirandon. Mirandon's playing is decorous, but I'm sure Gizavo really needs the extra cross-rhythms. If its ability to produce a mournful drone is the main reason the accordion travels so well, that doesn't mean it's not capable of rhythmic exuberance. Still, the combination suits Gizavo, whose playing revolves around swooning swoops or unexpected staccatos, both echoed in his engaging if hardly expansive voice. He shapes the vocal and instrumental lines quite freely, the one cutting across the other at one moment, both joyously together the next. In the ease in which it embraces Western possibilities, Gizavo's music paradoxically celebrates its wholeness. Pohjonen's music, like Cajun, gives voice to a fractured identity. That's not an assessment of value, only of difference: and we have the accordion to thank for it.

Tonight and tomorrow at the South Bank (0171-960 4242) and Canary Wharf (0171-418 2783)