One Sunday morning in March 1995 I was driving through the outskirts of south London, half-listening to the radio. The weather was grey and I was abstracted: deep in the middle of writing a new novel, I had reached that point where you can’t really think about much else. Then music unlike anything I had ever heard began to fill the car: breathy and high and beautiful, like wind, like rain, like human voices.

In the writing life of a book, and particularly perhaps a piece of fiction, there can come a time when everything within and around you seems to feed into it. Listening, I realised that I was experiencing a moment in which many things came together: children already half-written, with a life in a novel which was still developing, were also on the radio, making music which I knew, suddenly, they had always been meant to make on the page.

What I was hearing was a broadcast on Radio 3 of a concert given by the children of Brays Special School, in Birmingham. Working with a composer-in-residence, Duncan Chapman, they had been using simple, hand-held instruments, like the lovely “rainmaker”, and the most sophisticated new technology, to create their own composition. The result was extraordinary. Next morning I rang the producer.

I was put in touch with Paul Wright, the quietly inspired education officer of Sonic Arts, a national association of composers, performers and teachers. Its innovative schemes place composers such as Duncan Chapman in special schools up and down the country, working with music staff and providing imaginative software for use with electronic equipment that can be operated at a touch, or even a sound.

A Sonic Arts “workstation” can include the computer program Midigrid, which uses a simply steered box on the screen to trigger pre-recorded sounds, such as a child’s own voice. The Soundbeam ultrasound machine sends out an invisible beam, activated by the merest wave of the hand, to play another set of recordings. Multi-track tapes enable single sounds to be extended into longer musical gestures - complex “loops” or repetitions. The human voice can be played backwards; a digital sound processor can vary the pitch. The possibilities are endless, and offer children with profound learning disabilities the opportunity to take creative control over musical composition, producing work which, using both live and recorded sound, is both original and extraordinarily effective.

If ever there were benefits to be derived from the new technology, they are here, giving confidence and liberation to children and adults who, as Duncan Chapman describes them, are “quite disconnected from the world”.

It is a summer afternoon, and we are at William C Harvey School, in Haringey, north London. Outside, on the Broadwater Farm estate, tarmac paths bake in the heat, and beyond the slabs of shadow cast by tower blocks, the air is shimmering. Inside, in an upper-floor classroom, the windows are open, and the children are rehearsing for a concert, working with Duncan, with Katey Earle, headteacher and music co-ordinator, and with other members of staff.

A workstation on a table offers some of the Sonic Arts facilities. In the middle of the room is a microphone, and there are instruments: a wooden drum with six hollowed-out tunnels, each producing a different note; shakers and bells; and what Duncan calls a mousetrap - like a Jew’s harp, but plucked with the fingers.

And there are the children.

Some are in wheelchairs, some race about, one boy stands gazing at nothing, in a deep and impenetrable silence. Most are sitting on chairs, in a circle, next to teachers and helpers; few have speech, and much of the communication in this room is through sign, as well as the spoken word. And through music.

Duncan Chapman’s aim is to give these “disconnected” children the opportunity to make and explore the musical connection between self and sound - tapping, ringing, drumming, plucking, making sounds into the microphone - and then listen to themselves recorded, and make their own decisions about how the composition is to come together.

“Should this be loud or soft?” Duncan asks An, a tall, slender reed of a boy, twanging on the mousetrap. Loud, An indicates, clearly enjoying himself. He taps the wooden box, and Duncan taps with him; they work up a beat, and the communication between them becomes close and intense. Alongside, another boy turns up the volume on the recorder.

Where does a novel begin and end? These children breathe into the microphone; real life breathes in and out of fiction; music and writing both have their own mystery, as well as craft, which perhaps is one reason why I am so drawn to the work going on here.

But it is more than that. The central character in my latest novel, The Hours of the Night, is a poet: a virginal, reclusive, eccentric woman whose late discovery of love is both rapturous and painful. Gillian lives on the Welsh borders; on the other side of the valley is a school for children much like those I am watching now, from whom, instinctively, she shrinks. Not until near the close of the novel does she feel an affinity with them, and that is through the music they create, and her realisation that the haunting and mysterious sounds echo, in some way, the strangeness of her own childhood, her own inner life.

But much of this is yet to be written. What I am most aware of now is that the children in this classroom are, so far, less real to me than the people in the novel, with whom I have lived in silence for so long. Yet it is the children I am privileged to be watching with whom I must work on the page, travelling away from them, and deeper into fiction.

Discovery, falling in place, alchemy and transformation - whatever one calls it, and however one thinks of the writing process, there is a living nerve which connects the real and the imagined, and makes of it another world. I know of little more exciting than sensing that one has touched this nerve - however briefly, and with however modest success.

Later that summer, in the Queen Elizabeth Hall, I attend a concert given by the children of William C Harvey. Live and recorded music fills the auditorium; on stage, the children’s pleasure is almost palpable. Then, as on the radio broadcast which led me here, and deeper into my novel, it is hard not to think of the line which evokes the heart of the creative act: “And the Lord God breathed into his nostrils the breath of life, and man became a living soul.”

Sonic Arts is setting up a national centre in Yorkshire, scheduled to open in 2000. The project has received funding from the European Urban Cultural Regeneration Fund, including Pounds 250,000 for educational work. Around a quarter of Sonic Arts’s educational work is in special needs. Contact: Sonic Arts, Francis House, Francis Street, London SW1P 1DE. Tel: 01438 359344. E-mail: p.wright@SoundEd.demon.co.uk. The Hours of the Night, winner of the 1997 Romantic Novel of the Year Award, is published by Arrow, Pounds 5. 99