This paper introduces a novel collaborative environment (PESI) in whichperformers are not only free to move and interact with each other but wheretheir social interactions contribute to the sonic outcome. PESI system isdesigned for co-located collaboration and provides embodied and spatialopportunities for musical exploration. To evaluate PESI with skilled musicians,a user-test jam session was conducted. Musicians’ comments indicate that thesystem facilitates group interaction finely to bring up further intentions tomusical ideas. Results from our user-test jam session indicate that, through some modificationof the ’in-space’ response to the improvisation, and through more intuitiveinteractions with the ’on-body’ mobile instruments, we could make thecollaborative music activity a more engaging and active experience. Despitebeing only user-tested once with musicians, the group interview has raisedfruitful discussions on the precise details of the system components.Furthermore, the paradigms of musical interaction and social actions in groupactivities need to be questioned when we seek design requirements for such acollaborative environment. We introduced a system that we believe can open upnew ways of musical exploration in group music activity with a number ofmusicians. The system brings up the affordances of accessible technologieswhile creating opportunities for novel design applications to be explored. Ourresearch proposes further development of the system, focusing on movementbehavior in long-term interaction between performers. We plan to implement thisversion and evaluate design and implementation with distinct skilled musicians.