Techniques of performing involve providing interactive audio in addition to ambisonic audio in stereo tracks selected according to the occurrence of events in a media delivery system. For example, a user of a VR system observes a virtual environment that contains many virtual objects. The user may experience binaurally rendered audio played over N ambisonic channels from any number of virtual loudspeakers. In addition, the user may also activate another audio source by positioning his/her head at a certain angle, e.g., to look at a particular virtual object. As a specific example, when the user looks at a picture of a person, an audio track may play over a pair of stereo channels N+1 and N+2. Because they are stereo channels, there is no need to perform convolutions with HRTFs. In this way, audio may be provided for all virtual objects in the virtual environment with a small computational overhead.