Fever Ray, O2 Academy Brixton, London

Tonight's opening track, "If I Had a Heart", begins with a long, sawing build up of noise, before two green lasers shoot out at the crowd. The stage lights up, albeit too dimly to see the performers' faces (and they'll remain shrouded for the entire gig), as a series of old-fashioned lampshades pulse on and off, like jellyfish wafting through a murky sea. The synths wave over you and then the vocals arrive, with a murkiness and muddiness to match. The bass is so loud my nose begins to itch.

This is the world of Fever Ray, aka Karin Dreijer Anderson and band, aka one half of similarly intense electronic duo The Knife. She's only released one, eponymous, album so far – most of which gets an airing in tonight's fairly brief performance – but that album won huge critical acclaim and the crowd comfortably packs out the Brixton Academy.

Not that it's comfortable listening. Her voice live can be as sharp and as sourly powerful as it is on record. Wrung through a voice transformer, as on "Concrete Walls", it's a growl that sounds like it's escaped from a deep underground lair.

"Seven", one of the more catchy numbers, garners a whoop of recognition, as its crisp beats, wavering synths and ensnaring vocals take hold. While many of Anderson's lyrics get lost in the force of her delivery (and perhaps due to her Swedish inflections), those that break through twist the mundane into something really, you know, intense – as when she sings, darkly deadpan: "We talk about love, we talk about dishwasher tablets". Her invocation to "keep the streets empty for me", on a track of the same name, sounds eerily crucial as she sears it over the floating electronics, throbbing bass and clicking percussion. Even a twee Vashti Bunyan song, "Here Before", sounds treacly and sinister.

The only problem is that with such a fully realised musical fortress, you sometimes just admire the edifice rather than feeling part of it. One minute it's hypnotising and all encompassing; the next I've zoned out.