Hard heart, soft stroke

Banging things is the most elemental musical impulse, and anything you can hit can be a percussion instrument. No doubt that's why, for centuries, Western classical music placed percussion at the margins: too elemental, too fundamental, simply too exciting to be art. That has changed in the 20th century. The modern symphony orchestra might include half a dozen percussionists, a mighty battery of sound behind the main body of the orchestra, while percussion ensembles are an integral part of the fabric of music-making in a way quite inconceivable even half a century ago.

This week's BBC Proms concerts give a good sense of percussion's new prominence. On Sunday, Ensemble Modern performed Steve Reich's Music for Mallet Instruments, Voices and Organ, as well as Lou Harrison's Concerto for Organ and Percussion; on Wednesday Ensemble Bash offered more Reich alongside John Cage's music for prepared piano, music to remind us that the piano is, in essence, a percussion instrument. And tomorrow, Evelyn Glennie is the soloist in the world premiere of Jonathan Harvey's Percussion Concerto.

It's no exaggeration to suggest that percussion is the beating heart of 20th-century music, and not just as a pulse, but also offering an unprecedented wealth of timbral possibilities, from the most subtly evanescent to the most brutally violent. That's why the percussion kit is so large, and why a performance by Glennie so often resembles a gymnastic display as much as a conventional performance. A violinist has one instrument to cope with: a percussionist may have dozens.

That poses problems for a composer commissioned to write for percussion: which percussion? It's a problem that Jonathan Harvey initially found daunting: "This is the first time I've written for solo percussion, and my first response was that it was very difficult. I don't like the idea of building an enormous percussion edifice for each performance. I prefer to exploit Evelyn's virtuosity with the mallets, rather than having her worrying, `Can I get to the woodblocks in time?' I thought of pieces like James Wood's Marimba Concerto, and began to think something marimba-centric would be rather beautiful."

The next stage was to visit Glennie at home to work out what something "marimba-centric" might be: "I experimented, with Evelyn, quite a bit, listening to the different spectra a marimba produces, the brilliant and the soft, noting the instrument's peculiarities. It produces very varied sound, but what it doesn't do is sustain. On the other hand, it has a surprisingly long resonance. If you're not careful, it can sound too puddingy. And Evelyn warned me about the volume: not `I'll be drowned out' but `You'll have to watch the strings because I can drown them, and sometimes I can drown the woodwind too'. She'll be using mallets with a soft exterior but a hard heart, so if you whack, you get a very forthright sound, but a soft stroke is as gentle as cat's fur. That gives a wide range of timbres without Evelyn having to change sticks all the time."

But this is a percussion concerto, not a marimba concerto. While eschewing a percussion edifice, Harvey has not restricted himself to one solo instrument: "The marimba is the main instrument, but there's also a vibraphone, and two keyboards from a Balinese gamelan, big bulky things that Evelyn had bought on her travels and shipped over. She'd never played them in public, and was keen that I use them. Of course I loved them, they produce a wonderful spectrum of sound, but rather inharmonic, gong-like. It's not easy to tell what the note is, and they aren't tuned to either the slendro or the pelog tuning which are fairly standard in gamelan: I don't know how whoever tuned them arrived at these tunings, but I've scored the piece for untuned gamelan pitches. There's only one orchestra percussionist, and harp and piano often play with the vibraphone and marimba, but I wanted them at some distance from the soloist, to create a kind of antiphony. It's not a drummy, bangy kind of piece, it's a gamelan kind of piece."

The work also involves soloist and orchestra in canonic interplay, the one chasing and eventually overtaking the other. "I wouldn't call it a battle, but there is a dialectic," Harvey says. "Play has a lot to do with the piece, games with the soloist overtaking the orchestra. I hope people get this: I've tried to make it as clear as possible. I get lost in some of Bach's canons, for instance, which are perhaps not as characterised as they might be. He loved that hidden quality, the intricacy, but I trust that in my piece it's all made clear by the very simple structure."

For the past three years, Harvey has been Professor of Composition at the University of California at Stanford. Although the Percussion Concerto was not composed there, California has left its mark on the piece: "The scenery is beautiful, and I spent a lot of time looking at the Pacific, the play of light on water, the way the rip-currents interfere with each other. You have the waves coming in, going out again, currents cutting across that motion, just as in my piece the canons collide, form other things, then part. The slow movement is blurred and romantic in feel, with chords dissolving into each other, and ending very peacefully on a chord which is prolonged until near the very end of the last movement, which is one big shimmer."

At Stanford, Harvey has access to one of the most sophisticated electronic music laboratories in the world. A leading electro-acoustic composer, he is convinced, "Just as percussion grew throughout the 20th century, so electronics will be the next great musical thing, even in the conservative world of British concert-halls. I use synthesiser keyboards in most of my pieces, and samplers now have ever increasing amounts of memory: there's no limit to what you can trigger simply by pressing a key. Five or ten years ago, electronics tended to dominate any piece they were employed in. Now they're just like any other instrument, adding something strange and subtle. That seems very much the norm in Continental music. I don't completely understand why this country is, as ever, so backward. The way I'm moving now, the predominant impression is of live instruments, with electronics providing constellations of strange sounds blending in. But all these developments are only exciting as long as they lead to something which is musical, artistic, spiritual."

Harvey's use of the word "spiritual" risks associations with music quite different from his, but Harvey is first and foremost a spiritual composer: "For me, music is, in Buddhist terms, emptiness. It's play, it's dissolvable, anything can turn into anything else. Of course I want to create forms, figures, Gestalten, whatever you want to call them, and to give them all the support I can, both complex and coherent. But forms are formed, then abandoned. Music provides great emotional experiences, but ultimately they're just sand blown by the wind, like those Tibetan mandalas made of sand which simply float away. This meaning of music is very important to me, it's fundamental to how I see life: always impermanent, always changing, always shifting. What appears permanent can be shattered at any moment"n

Jonathan Harvey's `Percussion Concerto' is premiered tomorrow, 7.30pm, at the Royal Albert Hall, London SW7 (0171-589 8212), broadcast live on BBC Radio 3