Considered in the most general terms, the recording is a remarkable realization of a freely improvised timbral counterpoint. By putting lines made of sound color against each other, BRAC succeed in conserving the fundamental formal quality of the string quartet while working with a largely untraditional content. This isn't to say that more conventional pitches and phrases are absent; members of the quartet play elongated harmonized tones or sequences of tones at various points in the performance…