Our Open Symphony system reimagines the music experience for a digital age, fostering alliances between performer and audience and our digital selves. Open Symphony enables live participatory music performance where the audience actively engages in the music creation process. This is made possible by using state-of-the-art web technologies and data visualisation techniques. Through collaborations with local performers we will conduct a series of interactive music performance revolutionizing the performance experience both for performers and audiences. The system throws open music-creating possibilities to every participant and is a genuine novel way to demonstrate the field of Human Computer Interaction through computer-supported cooperative creation and multimodal music and visual perception.