Electromagnetic sensing systems allow for expressive interaction in electronic music, performance, and time-based media art. REBUS is a machine which emits and receives electromagnetic waves to form a sensing space where human movement and presence can be detected with previously unknown precision. The potential of the system is explored through a workshop and a study targeted to selected groups: whereas the workshop observed the approach of coders and musicians in proposing compositional methods that this electromagnetic field sensing instrument offers, the study inspected the behaviour of classical musicians, mainly trained on strings or keyboard instruments, vis-a-vis that of selected electronic musicians. The terrain between instrument and controller is also explored through a fruitful deception. The paper narrates the conceptual assumptions behind these experiences through an initial analysis and some reflections on the data collected
