ARTISTS Jaap Blonk and Joan la Barbara are babbling, but the audience is transfixed. They are using their voices as the input for an amazing performance at Ars Electronica, a week-long electronic arts extravaganza in Linz, Austria.

The performances include five groups of Australian artists, among them Linz-based Time's Up (http://www.timesup.org/), with Australian researcher Tim Boykett.

The group's work immerses individuals in acts that challenge space and gravity, such as Sensory Circus, Sonic Pong and SPIN.

Other Australian artists are Experimenta, the Next Wave Festival, Electrofringe and ACMI.

In Jaap and Joan's act, three enormous screens behind them display their sounds transformed into lines, curves and bubbles. The audience is equipped with 3D glasses and the objects float out towards the audience.

In one part of the performance, Jaap and Joan stand against a red background like a field of distress flares and seem to speak in streams of white lava and teal oil.

In another, they use their voices to paint: very basic, fat black lines for louder sounds, holding a note steady makes the line stay straight, pitch variations curve and where lines cross, colour appears vibrant.

Jaap paints dots with staccato "ha, ha, ha" sounds while Joan creates sweeping curlicues with trills and swooping notes.

"I was more driven by what I saw on the screen than by what I heard, but intuitively we use some things that relate to each other, some rhythms," Jaap says.

"There are certain tasks we're trying to accomplish," Joan says. "I'd like a little more control, but I think it's a matter of getting used to the instrument. There's also cross-talk between the two microphones. Sometimes I would be singing and doing a line, but because of what he was doing it would get jagged."

The creators of the software, Golan Levin and Zachary Lieberman, say it's early days. "Zach and I are software developers, more than software artists," Golan says.

"The work is about the relationship between sound and image. In the combination of the two, hopefully it succeeds. The ideal would be for Joan to walk away saying the audio is great, this is an album, and I could walk away saying the collaboration was great."

If this is just the beginning, the possibilities are impressive. What would come out if it was played with an aria? What sort of works will artists of the future create with this technology? There will be further performances in England in November (see http://www.ultrasound.ws/ and http://www.ica.org.uk/ for details).

Ars Electronica is at http://www.aec.at/. The centre has four floors of permanent exhibition (including a virtual reality cave with simulated time travel) and many other works exploring digital interface, haptics, music and more.

For the festival and the coveted Golden Nica of the Prix Ars Electronica, the exhibitions and installations have overflowed into at least four other venues.

In the Brucknerhaus, the electrolobby is filled with experimental works, including Trash Mirror, which reflects your shadow at you in a collection of lost bus tickets and packaging; and Switch, an interactive feature film from Denmark. In the Hauptplatz, an enormous climbing wall laid over big printed letters forms the TeleKletterGarten, a programming interface that requires bodily intervention.

Performances are scheduled twice daily, with coders relaxing on the couches below asking for the next letter through a microphone as climbers scramble across to the Enter key.

In the OK Centre, visitors can explore the winning works of the Prix, including the stunning animation Tim Tom, a student project from France (by comparison, last year's prize for animation went to Monsters).

This year's theme is Code, and Humboldt University-Berlin's Institute for Aesthetics music history and aesthetics professor Friedrich Kittler starts with a history of code, code as law, code as a set of instructions and code as language.

Electronic Frontier Foundation legal director Cindy Kohn discusses the legal implications of code as speech, and Smart Mobs author Howard Rheingold tells the audience "the battle over code is the battle over our ability to organise collectively".

"We need to take back the public sphere," he says. "We have opportunities for new technologies, new social forms, new cultural forms. It's important to stress that a smart mob is not necessarily a wise mob."

Around all this is woven a soundtrack of digital and analog music, from the cutting edge Blockjam, toy of the future, to Audiopad, a collaborative light interface for performance by James Patten and Ben Recht from MIT.

One Japanese work involves instruments that play themselves, including an automatic xylophone shaped like four flowers with moving petals.

Winner of the Golden Nica for interactive art is Blast Theory from the UK, which aims to be in Adelaide in February 2004, with a work called Can You See Me Now? It has real-world players chasing online players using GPS and WiFi.

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