Estimating vehicle speed by analyzing the acoustic frequency of dashboard camera sound

Dashboard cameras are now widely distributed and help determine the cause of traffic accidents and vehicle speed. The simplest method to calculate the accident vehicle's speed uses a specific section's driving distance and time, determining the average speed. However, we cannot determine whether the vehicle was accelerating or decelerating. In addition, setting the reference point of the specific road section is difficult if the video is too dark or the resolution is too low. Therefore, this study aimed to calculate vehicle speed using sound data from dashboard camera videos. Herein, we suggest a method to calculate the speed of a vehicle in an accident by analyzing the engine sound frequency. Furthermore, our method was verified experimentally and in an actual case. We found that this method could obtain more information than other dashboard camera speed calculations, such as when the vehicle accelerates, decelerates, and shifts gears. However, torque converter slips increased error in the speed calculations. Therefore, we propose using the engine's sound obtained from dashboard camera videos to calculate vehicle speed if the torque converter slip is not severe.