It took going to Flow to realise how deceptive its lineup is. As a Brit, at least, you see Blur and Devo and Christine & The Queens and Caroline Polachek on the bill and it’s quite enough to get you out to Helsinki. Jockstrap and Shygirl and Amyl & The Sniffers, and a lot of Finnish artists, who are supported extensively by the festival and crowd alike: if at any point you found yourself being swallowed by a blob of a few hundred people moving as one after an act had just finished, that act was always from the surrounding area.

With all of that going on, it was easy to miss that dub reggae legend Horace Andy was also playing, or to feel that there was plenty on the bill that you already knew about in order to completely dismiss the idea of discovering something as progressive but not party party as Scottish bagpiper Brìghde Chaimbeul. There’s nothing wrong with that – when I go to Wagamama I only ever order the chicken katsu curry in case I order something else and don’t like it as much. But discovering Chaimbeul on the first day of the festival made me look again at the lineup and catch something I’d almost missed altogether, also in the dark, factory-like room of the Other Sound x Sun Effects stage, which was Flow’s expertly curated space for the kind of experimental music that festivals booking Blur rarely also program: LA sound collagist Claire Rousay.

Rousay was responsible for one of the best avant garde (and electronic) albums of last year – Everything Perfect Is Already Here, a two-track-long record of the artist’s signature sparse sounds, made up of field recordings, voice notes, eerie crackles and environmental recordings. It was standing-room-only to hear Rousay recreate this “weird, cool, experimental stuff” last night, where we were all rewarded with what we wanted, but also got a long look at where she’s going next with her songwriting – essentially in a more conventional (yet extremely affecting) direction.

After introducing herself (and acknowledging how she doesn’t usually do that), Rousay tells us that she’s just come from Berlin where she smoked 100 cigarettes, “So I feel great.” She then assumed her sitting position behind a laptop and a few electronics, with a guitar in her lap. The opener is so bare for its first 3 minutes you can’t be sure that Rousay has actually started it yet. But it slowly comes to life – what sounds likes the sound of a printer, the rustle of a crisp packet, the ambient sounds of an open window on a day when nothing is happening. It could be the first half of ‘Distance Therapy’, but is more likely new track ‘Your First Armadillo’, released 2 days ago via Saddle Creek’s Document Series. It’s already a mystery to what makes this combination of everyday sounds feel so melancholy, profound and addictive, but clear to me that I will be staying for the whole of Rousay’s set, almost involuntarily.

Her second track is something we’ve never heard from her before – a sung song, played on a clean guitar, with autotune vocals, plus Rousay-esque crackles, tones and strangeness that make it sound like lost Bon Iver gold or something a The Postal Service would have no doubt loved to have done, but ultimately like only a piece Rousay could have made herself. “I’m drunk as ever,” she sings on the slow motion emo track, as a viola quietly scrapes and the guitar resembles Slint. “This is not your problem, this is not your fault / This is me trying to stay involved,” goes another of these new songs, one of which follows each of her collage instrumentals. It’s as if Rousay’s two styles come in pairs, and they really do compliment each other – wildly different, yet both transporting us to suburban America where it’s permanently night time, with the freaky, crunchy samples preventing the straight-up songs from merely sounding like soppy confessionals.

“It’s weird singing songs instead of the weird cool experimental stuff, so sorry if that’s what you’ve come for,” Rousay says halfway through. “And I’m talking in the middle of the set, which is not cool. So I’m two for two up here.”

There’s a distressing voice note as one track too (beginning: “It’s 4pm on Monday and I can’t stop sobbing”), another song where a flat tone breaks into a recording of a party, and another – the closer – called ‘t2v’, performed through a rudimental robotic voice simulator, where the robot itself is full of anxiety and doubt.

What Rousay does is magic, where, evidently, however she presents her music it lands as a massive gut punch, for all the things she says and all the things she doesn’t even need to. Parklife!