Canadian guitarist Michael Brook has a unique style of atmospheric music performance. His methods embrace infinite guitar sustain, FM programming and digital effects, and he has plenty to say on all three subjects.

CONFRONTED WITH MICHAEL BROOK IN THE FLESH, the easiest thing is to underestimate him. Everything about the unassuming, quietly-spoken Canadian suggests he actively wants not to be noticed, yet he's an accomplished musician, a technical innovator and a unique guitar player.

Apart from a small foray into the more conventional aspects of popular music as a session player for Martha and the Muffins, Brook's associations carry the highest of intellectual pedigrees. Among them are trumpeter Jon Hassell and both Brian and Roger Eno. It's in association with the last of these that he is currently playing live, taking a break in the middle of our conversation to perform. Afterwards, he describes himself as 'happy with reservations'.

'I'd say it went quite well for a first night but I'm hoping it'll go better. There were some good moments and no disasters; if you get that in the first night I think it's pretty good.'

The concert is an unusual affair. The conventional visual and performance emphases take a back seat to the creation of an atmosphere, subtle and delicate, within the concert hall. The lighting is subdued, the volume of the music well below rock concert norm. The audience sit silent throughout, but show through their applause that the event is well appreciated.

'There is a bit of a contradiction in presenting this live', says Brook, 'because it's not event-oriented music, both in terms of what happens in the music and in the way that we're presenting it. And there's virtually no performance aspect to it in that we're not grimacing or dancing around: it's not physically demanding music to play.

'It's something we've all been thinking about but, without trying to be clever, there's a good reason for presenting it this way. At the moment there isn't any music like this live, so giving people the opportunity to go and hear music that is quiet and not particularly eventful is a good thing. They don't really get the opportunity to do that otherwise.

'One problem that can arise is if someone expects something to happen that isn't going to. But this audience didn't seem to be expecting to see a great pyrotechnics display or anything like that. In that respect it was a good audience — better than I hoped for — which meant we could play quietly and do what we wanted.

'When I was rehearsing with Roger we got into a discussion about how we were both coming from exactly opposite directions, yet achieving basically the same results. If it were just being discussed verbally, you'd believe the two to be totally incompatible. He's a schooled musician. His pieces are all composed and he uses changes in key. Because his pieces are all set, it's down to whether or not he can capture the necessary mood for that piece.

'On the other hand, I'm not a particularly schooled musician. My pieces aren't set at all, so in each case it's a structured improvisation. Because of that, the piece is part of the mood — that's what improvisation is.

'But in each case it's the creation of that atmosphere that we're interested in, so the two aren't really very far apart. There are more similarities than dissimilarities in what eventually hits people's ears. It's surprising when you look at the things that have influenced him and the things that have influenced me, and how we go about making our music.'

BROOK'S PERFORMANCE IS A DELICATE SERIES of harmonic manoeuvres that allow him to conduct the listener on a guided tour of his moods. And unlike many 'improvisational' composers, Brook has an intimate understanding of his chosen musical structures.

'I almost always use the same notes, but sometimes I establish different chord centres — it's how you weight the notes you use. There's this beautiful thing that can happen with tonal ambiguity, where everything is obviously modal and you can reach a crosspoint, like a tonal dusk, where it's not evening and it's not day — if you do it right. You establish a key and then you keep playing the same notes and then you start emphasising another one that's still part of that mode. If I introduce a sequence, the sequence is usually in the new key so your ear starts saying: "oh, it's not in that key... oh, yeah it is...". But there's no dissonance or tonal stress involved.'

Meanwhile, the improvisational aspects of Brook's music mean that his sequencer programs, for example, are deliberately free of constrictions.

'With my sequences I can change tempo or reverse them, and some of them are purely rhythmic so I'm free to work over them. The big difference between using tapes and using sequencers is having the choice of what you put in and what you leave out. Having this bag of tricks where you can call on what you think is most appropriate is very important, especially in terms of it being a performance rather than a set piece or what might have happened in a recording studio.

'Something like Philip Glass' music is quite digital, in that it's either right or it's wrong. I saw his band a few years ago and I enjoyed it, but I thought I may as well hear the record, where I know they get it right. There's very little room for the flexibility that is inherent in something that is worthwhile performing. You have to have room to move, or it's either right or wrong; I felt there wasn't that room with his music, so it wasn't worth performing it.'

In contrast to Roger Eno's classical training and French minimalist background. Brook draws his current influences from his fascination with the East, and India in particular, following his study of Indian music with LaMonte Young in New York.

Brook's recent album, Hybrid, is a clear documentation of this fascination, and utilises drone notes set against seductive rhythmic soundscapes to create the mood of a modern, electronic India. The extensive use of sound-processing, and in particular multiple echo repeats, allows one musician to create a rich, gently moving tapestry of sound, a situation exaggerated by Brook's infinite sustain guitar.

There's nothing new about infinite sustain, of course, but the development of Brook's guitar-playing style and equipment is unique to him.

'When I started recording Hybrid I wanted to get an E-bow, so I phoned the guy and placed an order. I sent the money; it didn't come. So I phoned him again and he said it should be coming soon. Then I phoned him again... We went through all the standard bureaucratic bungling until it was obvious it wasn't going to come in time. But, as I built electronic gadgets anyway I wondered if I could build something that would do what I needed. I'd actually had the idea for quite a while, and I found out later that it works much better than the E-bow.

'I found I couldn't really use the E-bow — you have to pick it up and get it in the right position over a string before you get any sound. With the infinite guitar, you don't have those problems. I also bend notes a lot, and you can't really bend notes with the E-bow because you hit the next string, and you also can't use the vibrato arm, which I like to use a lot.

'My design is in the process of being patented at the moment so, although I'd like to, I can't say how it's done. What it lets you do is sustain a note for as long as you want. It means you don't have to pluck a string to start a note, so it's perfect for me. It means I can fade in notes without having to physically fade them in — they just start up on their own. It also allows you to get harmonics very easily. A lot of the drones on my album were guitar, and not synthesisers as you might imagine.

'I don't think I'll improve it any more because it suits my playing as it is — though obviously I don't know about other people's playing. But I'm more interested in creating music than developing the idea any further right now.'

"I found I couldn't really use the E-bow — you have to pick it up and get it in the right position over a string before you get any sound, and you can't really bend notes because you hit the next string."

ALTHOUGH BEST NOTED FOR HIS GUITAR WORK, Michael Brook also makes use of synthesised sound in the form of a Yamaha DX7, TX7 and a pair of TF1 modules in a TX816 rack. They don't play a particularly prominent part in his music, but they retain a strong individual identity courtesy of some sympathetic and effective programming — a rare feat in these days of FM preset mania. As it turns out, Brook has conducted a long affair with FM synthesis which extends as far back as the days of the system's initial development.

'I happened to be in school when John Chowning published his article on FM', he recalls. 'So I'd read about that, and I was working with a guy who was connected with Don Buchla. Buchla had FM at that time and it was linear FM — and that's the crucial point, because most oscillators then were exponential. If you use a linear response oscillator you just get a change in timbre as you increase the modulation index, whereas with exponential oscillators you get a change in pitch as well as timbre. So Buchla had FM synthesis in his system but it never seemed to me to do very much. This was in about 1975. Then he had a computer system with theoretical oscillators, and you could do any of the FM stuff with that but it was absolutely useless because it took weeks before you could hear anything. I wrote a couple of things on that and then I completely lost interest. It's a very academic way of dealing with sound and consequently of no interest to me whatsoever. I saw a couple of other computer music systems that had FM synthesis too, and they were just the same.

'Then, finally, Yamaha came up with the DXs and I thought: "Ah, so that's what happened to it all", and it turned out that they'd bought the rights to it so nobody could do it the way Chowning had proposed originally. I suppose I'd waited ten years for it to become usable.

'Now that they're around, I don't know why a lot of people in rock use DXs, because they're so much stronger in my area.

'I think the touch-sensitivity and the fact that you're not using filters but adding harmonics, are huge factors in their usefulness. The only area that they've missed out on for me is LFOs; I'd really have liked to see more than one LFO.'

Considering his obvious enthusiasm for the subject, it seems strange that Brook's involvement with electronics didn't embrace the delicate art of analogue synthesis during the pre-DX lull.

'I used to be really involved with synthesisers about ten years ago, but I lost interest over those ten years because they forced you to make trivial music in one way or another. You either did real avant-garde 'bleep bloop' stuff, or you were restricted to very simple melodies in pop music.

'I think the DXs are musical instruments, while most synthesisers aren't.'

A sweeping enough statement by anybody's standards, and one that can't be allowed to pass without some qualification...

'Analogue synths are valid for certain types of music, but it's only the DXs that apply to my music because you can get convincing ethnic instrument sounds on a DX, and you can't do that on any digital or subtractive type of synthesiser. I find I can get all the sounds I want from a DX.'

TO SUBSTANTIATE HIS CASE, BROOK HAS AT HIS FINGERTIPS the most believable tabla patch this author has ever heard.

'If only they'd make a DX with non-tempered tuning, I'd be in heaven. The Prophet 5 would allow you to use just intonation, but it wouldn't stay in tune so it was useless. One thing I have considered is putting more modules into the TX rack and using each module monophonically as a polyphonic system, so each module would have its own tuning. I'm sure you could work something out along those lines.

'It always sounds so academic, but I really believe it is significant. It's a very interesting area and I think there's a lot more to come from it.

'I saw a programme recently about a computer that allowed you to use just intonation monophonically', he muses.

And maybe this time, the delay between computer impracticality to commercial availability will involve Brook in something less than a ten-year wait.

In the meantime, the composer is keen to emphasise that his music also makes use of new technology in other areas.

'Most of what I do isn't just synthesisers', he says. 'It's delaying, harmonising and tracking things. I can build up chords by having feedback loops between the reverb and AMS. But you can get fooled watching me, because the guitar will keep going when I'm not actually playing it.'

Alongside that AMS and a Roland SRV2000 reverb, Brook has a brand-new Yamaha SPX90 multi-processor, and what is probably the largest private collection of old Electro Harmonix 16-second delays. He is equally enthusiastic about both.

'I actually don't use the AMS all that much these days, but those old delays are fantastic. The SPX thing is fantastic, too — really amazing. I need about five of them, that's how good it is. I'm actually thinking about buying one at the moment. The MIDI is useless, though. Nobody's implemented MIDI in a useful way on any of these things; all it means so far is that it saves pushing a button. It means you don't push it there, you push it here — that's all.'

Like so many musicians, though, Michael Brook has found technology to be a double-edged sword, creating as many problems as it solves unless kept in check.

'There's such a danger of becoming a one-man band if you're not careful. I don't think that really works for an audience, so I try to make my concerts more like a solo performer using a little extra sound-generation to help add texture to the music.'

In that, at least, Michael Brook has succeeded admirably. There should be more like him.