We present iSymphony, an interactive orchestral conducting system for digital audio and video that adaptively adjusts to the user's conducting style. Using a digital baton, users may control the tempo, volume, and instrument emphasis of a digital audio and video recording of an orchestra. The system adaptively recognizes three gesture profiles: the four-beat neutrallegato pattern, an up-down pattern, and random gestures. The system uses an audio time-stretching algorithm we developed that allows the playback speed of a digital audio recording to be arbitrarily adjusted without changing its pitch. iSymphony is an example of how computers can enable more people to experience an interaction style normally limited to a few people (conductors), and is installed as part of the It's Artastic! exhibit at the Betty Brinn Children's Museum in Milwaukee, USA.