In passive sensing such as human hearing, the direct-to-reverberant energy ratio (DRR) has been believed to be one of acoustical cues for estimating the distance to sound source. We examined the relation between fluctuation on frequency spectrum of interaural phase differences (IPDs) and long distance to motorcycle (to 30 meters) on the road. Short-term IPDs were utilized to estimate the distance to motorcycle using head and torso simulator, in which engine sound of motorcycle was passively detected. We describe motion detection of motorcycle approaching especially from behind by using head and torso simulator.