Localization system for urban search and rescue using smartphone microphones

Methods for rescuing survivors buried under rubble generated in earthquakes are urgently needed. In this study, we propose a method for searching for victims' smartphones using audible sound. A searcher generates dipole sound fields using four loudspeakers, which are measured by the victim's smartphone. Then, the azimuth of the smartphone in the searcher's coordinates is computed and transmitted to the searcher. The proposed method was validated via experiments conducted in a training field for earthquake disasters. The results revealed that the searcher can approach the smartphone by repeatedly estimating its direction and moving the sound source toward it.