Bass Emotions

On a stage in a cavernous, wooden space an L-shaped light picks out two people: Susan Stenger with a white bass guitar and Michael Clark lying on the floor. Stenger plays a sustained, repetitive and very loud bassline, while Clark, testing and flexing his limbs, appears to have just woken up. His movements are tentative and strangely elegant, as if he's arguing with the atmosphere or wrestling with an abstract compulsion. Fragments of stories told with a series of isolated gestures refuse to fuse as they hint with the subtlest of means about how complicated moving - whether it's ballet or yoga or just getting out of bed - can be. A weird dynamic is established between the solid grinding aggression of the bass and the almost modest probings of a body you somehow know could do more than this if it wanted to. It's like watching an Olympic sprinter taking a stroll.

Before his mood and limbs lighten up, Clark's dancing explores the way air can be a heavy thing to force a limb through. In an understated struggle towards the edge of the stage, he comes so close that for a moment it looks as if he might fall off. This isn't dance so much as a choreography of precarious discovery. Sometimes you have to test the parameters of the place you find yourself in to understand the limits of where you can go. Watching someone do this to themselves to the accompaniment of such floor-trembling noise is akin to witnessing a resurrection in the middle of a traffic jam.

He makes his way back from the edge with a limping energetic spring. Another dancer, Kate Coyne, joins him and after the intensity of what we've seen, asserts the primacy of flesh over spirit - she's the antithesis of fragility. She crackles with energy, moving from one area to another in a way that is immeasurably dignified and considered. But despite the links the music creates between them, all three are so deeply inside themselves, they hardly seem to interact - imagine observing researchers sharing a desk in a hushed library and being made gradually aware of their heartbeats. A single note becomes a shape, a complex body a single note. Isolated moments throb together and become a coherent, hypnotic whole.

The night continues. Dancers come and go like students in a hallucinatory academy, their formulaic movements dissolving into a demented parody of classical dance, before they collapse and drag each other across the stage. A young woman, her hands painted black, swims through the atmosphere, claps with the concentration of a lunatic and summons two drummers and a host of otherworldly visitors. Movement erupts with the explosiveness of introspective children forced to fight. Flashes of effervescent generosity light up the intense and all-pervasive inwardness. Things warm up.

Stenger's chamber orchestra of five electric bass guitars, Big Bottom - a mix of professional musicians Stenger and J. Mitch Flacko and artists Angela Bulloch, Cerith Wyn Evans and Tom Gidley - explodes into what sounds like a marriage between a life support system and heavy metal anthems without the corny lyrics. Playing famous bass riffs (Smoke on the Water, Sunshine of your Love, The Model, Ironman) and compositions by Stenger and Simon Pearson on the lowest possible notes causes vibrations to leap from the quintet in an intensely physical way.

The dancers' monochrome costumes, as keen to reveal the mechanisms of movement as they are to tease expectation, were designed by Hussein Chalayan, who pared them down to absurd, functional components - a sleeve, a G-string, a layered dress. At once delicate and sturdy they seem to brush against the sheer weight of the music before veering off into another realm - one a little quieter than this perhaps, where detail is privileged over the avalanche of sound that threatens to overwhelm them, but never does.

Is this a concert with dancers or a dance performance with music? Does it matter? It's hard to imagine the Royal Ballet hauling the orchestra on stage, but that's essentially what happened here. It makes you realise, in the way that all really great live music does, that sound can be as visible a medium as dance - and that dance still has an infinite number of abstract possibilities just waiting to be explored.