aCoUsMiXeR is a controller instrument used
to ‘mix’ or ‘project’ audio tracks in the space
according to the principles of acousmetry:

… Acousmetry is the discipline of perceiving geometric proportions by hearing. We don’t ask to the listener
“what do you hear?” but “what do you see?”…

… a new discipline, acousmetry, suitable to represent and make “visible” geometrical shapes with sounds. Such a discipline, well formalised, presents new capabilities of artistic expression ,..

The basic principle behind acusmetry is the MIDI protocol, aCoUsMiXeR port everything in the audio domain and provide the user with pitch/speed controls in addition to the canonical volume and panning.
Acousmetry was introduced and formalized by Francesco Rampichini

http://www.acusmetria.it
http://www.mariosalvucci.com/apps
http://www.synesthesiadesign.net