MobilePhoneOrchestra.com is an online platform for novices (or experts) developed to perform electronic polyphonic contemporary art music. The platform contains novel music instruments and animated notation to conduct a performance. The aim of this rehearsal session is to further explore the potentials of the platform for audience participation performances. More specifically, various exercises of performing spatial electronic music will be tested together with the audience and their mobile phones as instruments. In particular, the aim with this session is to experiment with ways on how to communicate performance instructions through graphics to the members of the mobile phone orchestra. The session will combine practical music performance exercises with an open discussion about participatory aspects in general and more specifically the experiences gained by the participating audience. No musical background is needed to participate