Abstract: The travel situation of a vehicle is detected by sensors and a sensor section 110 recognizes the moving state of the vehicle and outputs event signals. A processing section 180 has a sound emission control section that acquires a MIDI message to be used for notifying the travel situation by means of a MIDI sound source generating section. At the same time, it recognizes the priority level of the event signal to be used for notification in terms of urgency or significance and defines the parameter value of the MIDI message so as to bring the localized sound image of the sound to be emitted from a speaker located substantially at the center relative to a driver according to the priority level. Then, it has a sound emitting section 150 emit the sound.