TF Archives

Computer DJ uses biofeedback to pick tracks

Author: Duncan Graham-Rowe /
Monday, November 19, 2001
A computerised DJ that uses feedback from the dancers to generate new music has been developed by artificial intelligence experts at Hewlett-Packard, meaning clubbers may soon only have themselves to blame if they do not like the music they are dancing to.

Dave Cliff of HP's laboratories in Bristol says that the "HPDJ" will monitor the way dancers respond to the music and compose new tracks according to how animated the crowd becomes.

In 2000, New Scientist reported on an earlier version of the HPDJ and pitted it against a human DJ in a London venue to see how it fared with a live audience. Although the software managed to fool a third of the clubbers into believing a human DJ was at the turntables, our panel of professional DJs was more sceptical. But then again, they will be the ones to lose out if it works.

The earlier version takes dance tracks and works out the best sequence in which to play them. It can also mix them, seamlessly fading one song into the next while adjusting the tempo.

Cliff says that the biggest gripe that DJs such as BBC Radio 1's Judge Jules had with it was that it could not gauge the crowd's response to the music. That got Cliff thinking about ways to improve it.

Heart monitor
His solution is to give each clubber a device like a wristwatch that monitors their behaviour, feeding info back to the HPDJ via a "Bluetooth" wireless link. "It tracks your location, measures your heart and perspiration rate, and an accelerometer monitors how active you are," Cliff explains.

Every dance song comprises a number of different tracks, such as drum patterns, bass lines, keyboard hooks and vocals. To create a song, the HPDJ chooses tracks from a large library and then modifies and overlays them, based on the vibe coming from the dance floor.

So how does it work- The HPDJ uses a "genetic algorithm", a type of program inspired by evolution. It uses a survival-of-the-fittest approach to create new and better tunes.

In the case of the HPDJ, the different tracks are the "genes", and the inputs from the dancers are the "fitness" factors, essentially deciding whether or not particular combinations of genes survive.

Hitting the floor

If the track sounds so awful that people cannot get into it, they may wander off to the bar or dance less enthusiastically, says Cliff. So HPDJ will then try to improve the music, experimenting with different beats and bass lines, or speeding up the tempo in a bid to coax more people back onto the dance floor.

When the crowd gets into the music, the HPDJ will sense that more people are on the dance floor and monitor how actively they are dancing. It will then gradually build up the tempo to whip the dancers into a brief frenzy, before calming things down for a chill-out period.

Cliff also envisages a novel spin-off: the software could be linked to a CD recorder, so as you left a club you'd be given a CD with the music you helped to create.