Critical Point

In 2009 I had the honour of being a Visiting Scholar at Carnegie Mellon University's School of Music, where I collaborated with Prof. Roger Dannenberg by providing visuals for his piece Critical Point.

Critical Point is written for solo cello and an interactive computer-music system with two-to-four-channel sound and computer animation. The cellist plays from a score, while the computer records and transforms the cello sounds in various ways. Graphics and video are also projected. The computer-generated graphics are affected by audio from the live cellist. Critical Point was written in memory of the artist Rob Fisher.

The digital audio effects include a variety of techniques. The most frequently used processing combines pitch shifting with delay and feedback, creating complex polyphonic textures from the cello sound. Random algorithms sometimes modify delay and pitch-shift amounts rapidly, producing further complexity and variation.

The inspiration for the images came directly from Fisher’s work. The animation mixes reactive graphics generated in real time with short segments of recorded video.

The animation process is roughly synchronised to the performance, yet maintains a degree of autonomy. The software processes the sonic output in real time and receives synchronisation messages from Dannenberg's audio-processing system.

Critical Point was premièred in 2009 by the Pittsburgh New Music Ensemble. It was subsequently performed at the 10th International Symposium on Computer Music Multidisciplinary Research in Marseille; the Australasian Computer Music Conference in Canberra; the CHI 2010 Media Showcase; and the Seoul International Computer Music Festival.