We present an assistive suitcase system, BBeep, for supporting blind people when walking through crowded environments. BBeep uses pre-emptive sound notifcations to help clear a path by alerting both the user and nearby pedestrians about the potential risk of collision. BBeep triggers notifcations by tracking pedestrians, predicting their future position in real-time, and provides sound notifcations only when it anticipates a future collision. We investigate how diferent types and timings of sound afect nearby pedestrian behavior. In our experiments, we found that sound emission timing has a signifcant impact on nearby pedestrian trajectories when compared to diferent sound types. Based on these fndings, we performed a real-world user study at an international airport, where blind participants navigated with the suitcase in crowded areas. We observed that the proposed system signifcantly reduces the number of imminent collisions.