The curved ceiling of Modern Art Oxford’s basement room looms low over the stage as the audience drifts down the stairs and takes a seat. The small room is full and warm. On the stage is an enormous desk covered in a bank of equipment: a complicated mass of multicoloured cables and blinking red LEDs, looking like a 1970s sci-fi film vision of the future.

When Mountains take the stage, they look more as if they’re about to go on a fishing trip than preparing to play a show. There is not much of a preamble: after tuning up a pair of guitars, the Brooklyn duo introduce themselves and then settle down to the business of engineering their intricate three-movement soundscape. Mountains are well known for slowly building layers of texture into their compositions, and tonight is no exception. After manipulating synthesised sound waves until the throbbing rhythm fills the basement, guitars are woven into the mix to add an organic element, a human touch to the technical process that is taking place in front of us. A drawback of live performances of experimental music is that they are often visually underwhelming – Mountains get around this by the strength of the imagery in their pieces. There are deep glacial rifts of slow-building high-notes; a light rainstorm of synthesised marimba scales; staccato keyboard notes and pizzicato-brief guitar jabs and a Morse-code message played on a mournful violin. It is elements such as these that bring a warmth and closeness to the performance. A pair of huge speakers is pointing towards the audience, with another set directed at the stage, and it’s this more than anything else that seems to bring the performers closer to us – we are enveloped by the music and respond, as do the artists in front of us, albeit we respond emotionally while they respond physically, deftly manipulating the gear and surfing on the crest of the sound waves. In the final minutes of the set, the omnipresent bass notes are thick and heavy, yet comforting like an eiderdown; and when the final reverberations die away the atmosphere feels noticeably cooler.

In the moments before Tim Hecker appears, all the lights in the basement are extinguished, leaving the Montreal sound-artist illuminated solely by his tiny desk lamp and the ambient glow from his gear. While Mountains managed to draw the audience into their performance, Hecker wishes the opposite: the darkness has the effect of dividing the hall, and we become isolated individuals, left to experience our own response to the music. The first movement of his performance is mechanical and heavy, with a threatening bassline producing an intangible turbulence that feels as though we are sitting on the hard shoulder of a motorway, watching heavy goods vehicles heave past us. While the bass throbs rhythmically, Hecker punctuates it with bursts of white noise or a loud, abrasive chord; never letting the audience settle into a complacent passivity but instead forcing a reaction – an almost physical response akin to the sudden sight of a dilapidated steelworks in an otherwise tranquil pastoral scene. In his second piece, Hecker instils a false sense of security through sparsely beautiful piano notes, before a braying noise like a faulty chainsaw weighs in, shattering the illusion and keeping us alert for future deceptions. They come quickly – a discordant note to create a sense of uneasiness, a minor arpeggio which builds a cautious optimism before dying away into a percussive rattling that sounds like a cabasa made from human teeth. Despite the ominous build-up, however, that feeling of optimism continues to burst through the wall of noise in the form of a spooky piano scale or a whirring treble reverberation; playing to the image that the relationship between creation and decay is cyclical – that even something great, once built, must be demolished to make way for something else to come in the future. The set builds to an open conclusion, sonic layers continuing to rebound around the room although without a showy finale, as though we are expected to continue the inexorable cycle of creation and demolition ourselves, in our own way. And thus, uttering a monosyllabic “thanks,” Hecker vanishes into the ether.