Critical Point is written for solo cello and interactive computer music system with two to four channel sound system and computer animation. The cellist plays from a score, and 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 is written in memory of the artist Rob Fisher.
The digital audio effects include a variety of techniques. The most often used processing is a combination of pitch shifting with delay and feedback. This is used to create complex polyphonic textures of cello sound. Sometimes, random algorithms are used to modify the delay and pitch shift amounts rapidly, resulting in even more complexity and variation.
The inspiration for the images came directly from Rob Fisher’s work. The animation mixes reactive graphics generated in real time with short segments of recorded video. The images are intended for projection onto the cellist who performs near the projection screen or surface, playing with the canvas/performer relationship.
The animation process is roughly synchronized to the performance, yet it maintains a certain autonomy. The constructed software processes the sonic output in real time, and receives synchronization messages from Dannenberg's audio processing system.
Critical Point was premièred in 2009 at Pittsburgh New Media Ensemble, and was also performed at the 10th International Symposium on Computer Music Multidisciplinary Research, in Marseille, France; at the Australasian Computer Music Conference, in Canberra, Australia; and at CHI 2010's Media Showcase (CHI's presentation).