With impeccable timing, just as I'm about to try to describe why the rolling, ecstatic power-drones of Chris Corsano and Mick Flower are such a blast, shamanic Old Time Relijun vocalist Arrington de Dionyso sends me a link to an article about Henry Flynt and his concept of the Hallucinogenic/Ecstatic Sound Environment. The conceptualist, musician, philosopher and contrarian Flynt was inspired to coin the term after hearing a piece by CC Hennix – appropriately, an improvising drummer, as well as a student of Indian music and a mathematician. "The HESE typically uses modal scales and sensuously appealing timbres which fill the audio spectrum," went his programme notes to a performance of Hennix's 'Electric Harpsichord'. "The audio programs consist of semi-regular processes, but they are multi-layered and micro-irregular, producing variable diffraction effects. The listener's attention is monopolized; the physical vibration is physically felt; the uniformity of texture produces a sense that time is suspended."

OK, so Flower/Corsano don't build their music from advanced mathematics, more the intuitive logic of friendship and honed improvising skills; nor, I don't think, are they intending to cause waking dreams or hallucinations. But those who witness one of their performances, at which Flower pulls endless solos from a strange long instrument with typewriter keys that perches incongruously on an ironing board, while Corsano manipulates kit, gongs, bells and junk like a one-man gamelan ensemble, frequently leave feeling a little unusual, certainly monopolized, transformed, wide-eyed with the thrill of having been pulled upward to a place of high-volume, perpetually mobile percussion and strings and left there for a bit longer than is normal. Both are veterans of experimental and transformative music: Flower is a founder member of Leeds' brilliant Vibracathedral Orchestra – makers of intense, DIY bliss-noise since the 1990s – while Corsano is one of the most prolific drummers around, turning his hand to collaborations with artists from Joe McPhee and Evan Parker to Björk (it's he who supplies the pots-and-pans beat on Volta's 'Earth Intruders'). Two albums, The Radiant Mirror and Four Aims, as well as live release The Chocolate Cities, mine the seemingly simple combination of drums/percussion and Flower's shahi baaja, known also as a Japan banjo, repeatedly and joyously. There are occasional forays into other sounds and instruments, but the flow rarely falters, held in a psychedelic mesh of sympathetic strings and thunder-clatter beats.

In advance of Flower/Corsano's appearance at Field Day, I spoke to Chris Corsano about tablas, home recordings and being an improv nerd. We didn't discuss variable diffraction effects.

How did it fall into place, playing as a duo?

Chris Corsano: Mick asked me to do a show with him when I moved over to Manchester in 2005. We knew each other before and had played together in a larger group once or twice. He was starting to do the Japan banjo stuff – I didn't know what to expect; I never even saw the instrument before the gig! We both agreed that it was fun and we should do it more, and he was just an hour's bus ride away in Leeds.

It's quite an odd instrument. Was it a challenge to play with as a drummer?

CC: It was easy right from the start. It's also the way Mick plays it – I don't think he'd ever seen it played before playing it himself. He's searched out how it's used, and it doesn't seem like it's a classical instrument, more like a folk instrument, maybe even a practice instrument. It's in some Persian music so it pops up in different places – there's a Japanese version, Mick's is made in India and it's like a souped up version of a bulbul tarang. I don't know, I thought I was playing with the instrument so much as playing with Mick: it seemed like an extension of him and his personality. There was a lot of room to play free but at the same time, more than anything else I was doing at the time, it had this pulse. But it was super loose and you could just float in and out of time-based playing on the drums. So for me it was really natural, and also a little bit new. From instruments I've played with before it sounded closest to guitar, but not like anyone else I'd played with who played guitar. It opened up another side of my own playing, which is what you look for in any kind of relationship: you access a different part of your own personality.

I've seen you play a few times and there is this sense of flow throughout – it does change, coming together and then going into more fragmented stuff, but there's still a flow, which is perhaps a bit more unusual for you?

CC: Yeah, I would say so. For a long time, it's tended to be just one long piece – maybe I'm joking around a little bit, but with Mick it's like we have one song and we play it each time and it's always a little bit different. I know that's a thing with most improv, but with us it feels like a really long song, like if this is our 50th show, this is part fifty. So it's stepping in and out of not just time, but structure. Maybe it's a little psychedelic, or the way psychedelic music looked to Indian music: a different notion of how to divide things up.

When you play shows do you have set starting points? Do you discuss how you're going to play?

CC: Most of the time it just starts where it starts and goes from there. I'm not really into trying to plan something; I'd rather let it develop. Every once in a while we'll do something that's more equipment-based, or if it's a room full of people who are talking, that might be an issue, like if we get into doing something quiet it'll get talked over. Or I have some prepared stuff that usually I can just throw on or off, but if it's broken or I'm borrowing a kit, it might take some time... but then it quickly tries to undermine itself; whenever I talk about that kind of planning there's an impulse to try and ruin it as fast as possible and go someplace that isn't planned.

On the record [Four Aims] we cut things up in song structures, in a more editing style, and used the fact that it was a record and not a live thing to have it be more of an experiment in the range of sounds we have.

You can hear that in Four Aims where the songs have quite different sounds. There's one track where you play the cello, for example.

CC: Barely – I saw the cello! One note, just for that drone... That was our second record and [we wanted to] to have it be different from the first one, which was: play, roll tape, and not even cut it up very much. So the second record was messing around with the expectations the first one would have put out there, and the expectations people have about bands' second records, that things get more orchestrated and you see failed attempts at getting grandiose. So it was a bit of a joke, this was our version of, you know, strings or having the orchestra come in and all that kind of crap [laughs]. It's always to entertain and to keep ourselves interested...I like the methods we use most of the time but it's nice to try some different sorts of feelings, which the second record did.

What's it like recording together?

CC: The first one [Radiant Mirror], we played a gig the night before, left the stuff set up, slept, woke up, went back to the place we played the gig and just played with microphones on us, so it was like a gig without anyone there. The second record was mostly recorded at Mick's house, with just a couple of mics set up. We've never been into a studio, so there's never been that thing of a place that sounds unnatural, with weird baffles or headphones – for us so far the recording process has just been an extension of how we've done things already, which I like. The second record felt special because it was from Mick's house, and Mick's house is great, it's a very welcoming spot.

Is he one of those people who has loads of stuff? I can imagine him amassing a lot of interesting instruments and bits and pieces.

CC: Totally, yeah, you nailed it. I guess that's where the cello showed up on the recording, and a harmonium...In a studio sometimes they have that sort of thing, where you can stretch out and try new stuff; Mick's house was like that but without the weird carpet and sound insulation. Not to knock studios, they can be great, but I prefer the home style, when it can be a home style like Mick's.

Because Mick is playing an Indian instrument – although he's not playing it in a particularly Indian way – do ideas from Indian music feed into your music. For example, does tabla music influence the way you drum with Mick?

CC: I have things that might have the really fast, articulated, melodic aspects of tabla playing. I wouldn't be able to do them on a tabla and I'm not trying to copy that, but there's a reason – it's like food combinations, after a while tomato and basil does go well together – so it's combining Mick's really fast [playing], sort of like a sitar player doing fast runs, but you also have this drone element, and this really expansive element, so what would work there would be akin to tabla playing, so then maybe some stuff with bells and different kinds of mallets, so it doesn't exactly sound like drums... It's maybe about trying to get at some of the same places that Indian music succeeds for me when I listen to it. Not directly quoting, but being aware of the history. Maybe it would be different if I knew more about Indian music: I do like lot of it but I'm not by any means an expert and I have other things I'm more comfortable drawing on. With Indian music I feel like I would have no right, not because it's a cultural thing but because I don't want to do a half-assed version.

I get the impression that the drone in itself is important to both you and Mick.

CC: I don't really think of that – it's different when you're on the inside. Maybe with some improv stuff you're very conscious of watching sound event after sound event, but with Mick's playing it's like this additive thing where cumulatively it adds up and you've got a giant drone. I'm conscious that it's there, but for me it's more, I don't know, more trees, less forest. That's just my relationship to it because I'm moving a lot – I'm much more active than a listener would maybe want to be – it's not like aerobic music, or even dance music necessarily [laughs], but because I have to be active to make it, I'm doing my own little aerobic workout to keep up with Mick.

You often build up the volume very quickly when you play live – is that because you're playing in front of people, or does it just happen?

CC: There's a tension and release, because once you get there, if you stayed up there the whole time it might be too punishing or tiring for the listener, but yeah, when there's no predetermined structure, it's hard not to get excited about a run that Mick'll play and then I'll play a little bit louder, and then we get in to this volume thing. It doesn't take long to have things snowball, usually in the loud direction. I think it has its own natural timing; it's maybe about that excitement, that ecstatic impulse, that you just want to rush there...Also we play more rock clubs than other places where a quiet thing would be appropriate.

If you look at the Field Day lineup you're the only improvising band playing, but I think you appeal to people who wouldn't normally think they liked improvised music or jazz or whatever. There's a sense that you can get swept up and absorbed into it anyway.

CC: I hope so. For me, being a kind of improv nerd, I'm always trying to sneak improv into people's diet. People have preconceived notions sometimes; or the way it's presented some of the time takes the fun out of it. But if you can keep all the great musicianship and attention to tone, everything I get out of improv, and make it relevant to a wider audience, I don't see anything wrong with that. That's not why I set out with any band, but it naturally happens because I like quiet, 'insect-music' improv music, and then I'll also be into full-on rock. Maybe people don't even know what we're doing is improvised and maybe they don't care, which is fine by me, but if someone wants to fall down that improv hole...I'm totally into the possibilities that you can come up with amazing stuff through evolving in real time, just seeing how many combinations you can arrive at by not having one person sit down and write everything out beforehand. I guess it's cool that we can hop on a bill with other acts and the music stands up. There is no reason to play music just because of the form, but if the content's good then it helps validate the music to people who are unfamiliar with the form.

Is it strange playing together after long periods of time, as you live in separate countries now? Are you going to get to practise?

CC: We've never lived in the same town, and after a certain point when I moved to Edinburgh, I don't think we ever had a rehearsal after that, so it was only gigs. I try not to go too long without playing with Mick, so it always feels like we picked up where we left off. And sometimes the time in between is nice because weird things seem to develop from nowhere, which maybe is to do with Mick going off for a few months doing his thing, and I'm doing mine, and then I've got this new little piece of metal...

I was going to ask, do you show up with new bits of kit? You always seem to have new bits and pieces.

CC: Yeah, my solo stuff is really for me a time to investigate all those little pieces of junk that I find! It'll give a slightly different flavour to each of the tours, especially if I'm flying over, I can't bring all of that crap [laughs], so I'll just bring one thing, and that'll be the tour where there was a lot of melodica...but it's that thing about a really glacial pace of development – anyone who heard our first show and who hears our Field Day show would recognise it's the same band, but that there are little things that evolve along the way.

Flower/Corsano play the Village Mentality Stage in association with The Quietus this Saturday, 31 July. For tickets and more information, visit the Field Day website