Wolfgang Voigt as Gas, Barbican

It comes to something when the logic of a German act calling themselves “Gas” is the least troubling element of a perfomance. Not that Wolfgang Voigt's ambient music, or the slowly-evolving digital art of Petra Hollenbach projected on the Barbican's cinema screen, contained any obvious shock tactics – but the whole 80 minutes created just about as unsettling an experience as one could imagine from abstracted sound and image.

As a club music producer and as one of the co-founders of Cologne's Kompakt label, Voigt has been responsible for some of the most emotive and lastingly affective techno records ever made. But it was his records made as Gas in the late 1990s that cemented his reputation in the wider artistic world.  Cramming modern orchestral composition and high-tech sound synthesis into densely compressed drones surrounded by a miasma of the crackle and hiss of radio, rain and fire, he both eroded the borders between nightclub and concert hall and created sounds which are only now coming into popular culture via the likes of Burial.

In the Barbican cinema we had a brief glimpse of Voigt in sharply-tailored velvet suit before the lights went down and he bent over his laptop to soundtrack Hollenbach's visuals. There was no clue as to what he was actually doing, any attempt to discern whether he was really altering his previously-recorded music was baffled by the diffuse edges of every sound that came out over the soundsystem, and the shifting, criss-crossing three-dimensional shapes across the cinema screen dominated all. Indeed to even approach what was presented within the unpleasantly throbbing waves of bass and crackle as music per se would have been to get its place within the wider work wrong, and to fundamentally misunderstand "ambient".

What we experienced was a set of games played with expectation. The projected visuals, in keeping with previous Gas artwork, began with – and kept returning to – the meshed branches of forests in the night. But from this dark northern European archetypal place of fear and fairytale danger, using digital processing they extrapolated a geometry of discomfort: a set of ugly anti-patterns that created a sick mockery of everything from blood vessels to galactic structures, making branches smaller as they came closer and larger as they faded away, making the irregular regular and the regular irregular, tesselating random patterns into new regularities and making expected natural growths spurt out in every wrong direction like cancer cells or bad jokes.

All of these visuals in their ghastly tricks with scale and dimension - seething details would accumulate and duplicate constantly so as to overwhelm the senses, and the abstractions from living human and plant tropes teased our sense of pattern recognition but only ever gave a grotesque mutation of what it was expecting - kept a constant sense of zooming vertigo which matched Voigt's sound's refusal to settle. Like My Bloody Valentine circa Loveless, any chord that he hit upon swerved around its root in seasick fashion, these shifting chords and harmonics always bursting to let a melody out which never quite came - while the few regular rhythmic techno pulses that came into the audio filed were dissipated so much that the beat became a ragged thrum from somewhere else, not a demand of bodily presence in the here-and-now as a dance music kick drum would normally be expected be. Meanwhile the night forest branches were miscoloured, discoloured, digitally manipulated to become scorpionfish fins, locust limbs, rotting feathers, a praying mantis version of the erotic silhouettes at the start of Bond movies, a Bosch hell as painted by a trapeze-act obsessed limb-stretching Tom Of Finland then viewed in a stereoscopic kaleidoscope, a simple blurry glaring blob.

Every time we thought we had the three-dimensional patterns on screen nailed as representing impurities in ice, or rotting Sargasso seaweed, or a grid of 100,000 cherry blossoms diffracting into 900,000 mosquitos trapped in destructive sex acts, the frame would shift, the vertigo would again set in, the patterns would be retesselated, and the blurring thrum of the soundtrack would remind us of the inhuman, non-representational abstraction of the total artwork we were consuming. Every time the three-dimensional grids that took up our field of vision suggested that relief from the onslaught was about to come, we just saw more confusion, never the hoped-for empty space.  The eye was never allowed to rest and neither was the mind, the whole evoking Stanislaw Lem's vision of Solaris, a living planet too vast and infinitely complex for frail human intelligence to begin to comprehend.

Even when the strobes set in for the finale, the photographic renditions of trees splashed with unnatural green and oversaturated light that flickered like lightning or war, the impossibility of it all continued to hit us in abstract fashion rather than spell out any message.  And so it should be. This incomparably horrible experience was not “about” anything, and it didn't tell us anything. It was what it was, and what it was existed at the very far edge of enjoyment. But its relentless unsettling was not, I repeat, about shock tactics – and the power of the destruction of oppositions between near and far, blurred and sharp, pure and cankered, living and non-living, regular and irregular, tranquility and aggression left the entire audience of the second sell-out show of the night breathless but nonetheless standing to applaud at the end, for the complete refusal of signification nevertheless had a huge power in itself.

The “GAS” logo zooming towards us in red on a finally-clear black screen at the end, like the infinite hideous complexity that preceded it, the ugly abstact expressionism in four dimensions, could not be justified as a pleasant thing and was hardly even a relief, but made for a bold finish to a bold work that left us in need of time to recover as well as to contemplate what had just happened.

Check out what's on at the Barbican Centre this season