Kapow! With one bound he was free

Who was it who said ''I prefer radio to television because the scenery's so much better''? Listening to Dirk Maggs's award-winning ''audiomovies'' of Judge Dredd and The Amazing Spiderman is like hearing sound in colour, or watching a Cinemascope film with your eyes shut. "I believe in using the gut power and dynamics of rock music and the panache of cinema soundtracks," he explains. "Audio is the ultimate visual medium. It bypasses the optic nerve and sneaks in via the side door. The visual cortex obligingly creates an image to suit - and you're away."

There are good precedents for the Maggs approach. In the 1940s and 1950s, when the wireless had all the pulling power of television today, screen stars always recorded special versions of their films for radio, bending over mikes like the cast of The Archers.

It is a sign of the present seismic shift in the fortunes and quality of the audiobooks industry that a clutch of movie greats (Humphrey Bogart, Sidney Greenstreet and Peter Lorre in The Maltese Falcon, Orson Welles in The War of the Worlds, John Wayne in Stagecoach, Laurence Olivier in Dr Jekyll and Mr Hyde) are now being marketed by an innovative little company called Heritage Media. The spoken word has not only come of age; it is rapidly acquiring a history.

But there is a world of difference between these period pieces and the seriously brain-invasive Maggs experience. Part of the secret lies in the use of Dolby Surround, a digital technology which creates startling spatial effects. During a fight between the boy wonder and the dread old- Etonian pirate Captain Hook in Maggs's Peter Pan, a sword somersaults over Pan's head (and, apparently, the listener's) to land quivering in the ship's deck with a reverberating ''boi-oi-oi-oing'' which you can almost see.

How do they do that? I drive to the Soundhouse in Shepherd's Bush to find out. Maggs is a smiley man in his late thirties, radiant with energy. He and his sound-mixer cum business partner, Paul Deeley, show me round their new studio with all the delight of a couple of boys given a train set for Christmas.

"Looks just like an ordinary room, give or take a couple of dozen mikes, doesn't it? But I lift this trapdoor and...'' Scrunch go his shoes on a bed of gravel. ''Or this one''. Paving stones. Then wood blocks, then earth. A cupboard holds more props - a roll of carpet labelled ''BODY'', various mighty staves and a cloak of invisibility.

In the control room next door, the console is like the flight deck of a Boeing 727. A PowerMac is running a programme called ProTool. Never mind sound without pictures; this is pictures of sound. Move the mouse, and colour squiggles show the mixer just what is happening to all the different elements being built into the track. They can be reduced and enlarged to be seen by the hour or millisecond, cut and pasted like words on a word processor.

One of the advantages of Dolby Surround is hugely improved clarity. "I've always liked a layering approach with effects," Maggs says. "What they call 'Foley', after the Hollywood sound technician George Foley who moved cinema on from spot effects to a continuum of different sounds added on afterwards. Surround means you can use these far more effectively - instead of running into each other like watercolours, they stay distinct."

Maggs settles me in the central "pilot" seat and, muttering lovingly over his favourites, selects a CD of effects. A second of action can have half a dozen different elements. "Dredd / mo'bike / start" combines a squeaky chain, two kinds of depth charge, revs from a Harley Davidson, a jet turbine, a skid and Concorde.

I find myself squawking Lois Lane-like in capitals and exclamation marks. "UNBELIEVABLE!!! But how can you HEAR X-Ray vision? Or Kryptonite, fer Krissake? Or SQUIDGY STOMACH?" He plays them. I concede defeat. This is the onomatopoeic comicspeak of 'kerrplunk!', 'Verrooom' and 'Aarrgghh!' made aural flesh.

Speakers in the round and many-layered sound effects are only part of the magic. Custom-made music (Brian May of Queen wrote the music for Judge Dredd, plenty of wit and humour ("We'd turn into the most terrible anoraks if we took it all seriously") and a razor-sharp sense of timing are equally essential elements. It is no accident that Maggs was a drummer before the 15 years he spent with the BBC, first as a studio manager, then as a producer for Radio Light Entertainment. "I remember Dennis Main Wilson, producer of Hancock's Half Hour, The Goon Show and 'Til Death Us Do Part, saying to me that the producers with the best sense of timing in light entertainment tend to have been musicians. And the drummers were the best of all, he said. They knew when to drop the bombs."

Having left the BBC and set up with Deeley of Soundhouse, Maggs is keen to avoid being tagged a comicbooks man. The huge success of their Radio 4 Peter Pan has changed all that, and as Audio Movies Ltd they have just completed a mesmerisingly exciting Gospel According to St Luke for transmission on an evangelical US radio channel. "I'd love to do a Shakespeare - King Lear for example. Or even Jane Austen. But I'm just as interested in a minimalist approach. A single-voice reading can be incredibly powerful - if it's approached with conviction and attack."

Going back to conventional talking-books after listening to a Maggs production is like eating ship's biscuit after Christmas cake. But there are disadvantages to audiomovies. They demand rather more attention than the cultured drone of the average audioreader. Driving round Shepherd's Bush roundabout just as Spiderman engaged in a vicious duel with Dr Octopus above the heads of a gasping crowd, I was myself nearly exterminated - by an all too real ambulance charging at full tilt. I had assumed that its blaring siren was just part of the audio action.

'Peter Pan' and 'The Amazing Spiderman' are now on cassette (BBC pounds 7.99). 'Judge Dredd' is on Polygram (pounds 7.99). 'Batman: Knightfall' broadcast by Radio 1 in April