We developed a signal sound which robustly inform citizens of disaster information even if speech signal is hardly intelligible because of long-path echoes and intense background noise. To do this research, we examined various factors required to develop such a signal sound under actual out-door conditions as well as laboratory (in-door) conditions with long-path echoes by use of multidimensional psychophysical evaluation for several candidate signal sounds as well as some other alarm signal sounds. Based on the experiments, we have finally chosen a single good candidate sign sound.
