TouchNoise is a multitouch interface for creative work with noise. It allows direct and indirect manipulation of sound particles, which are added together in a panning and frequency space. Based on the mechanics of a multiagent system and flocking algorithms, novel possibilities for the creation and modulation of noise and harmonic spectra are supported. TouchNoise underwent extensive revisions and extensions throughout a three-year, iterative development process. This article provides a comprehensive overview of the final TouchNoise concept and its approach to mapping and interaction, from which a variety of unique sonic capabilities derives. This article is based on our experiences with a fully functional prototype implementation, and focuses on the systematic exploration and discussion of these new sonic capabilities and corresponding playing techniques, which differ strongly from traditional synthesis interfaces.