Optimization of Position of Siren Speakers to Raise Awareness of the Ambulance at Intersections

Abstract

In 2017, we proposed a new siren system of the ambulance for early perception of its existence or approach. The system has four siren speakers, two on the front and one on each body side. When passing through an intersection or changing a lane, the ambulance crews produce a rapid increase in sound pressure by turning on the side speakers. Since the siren blows from four speakers simultaneously, the sound interference occurs, that is, the sound pressure differs according to location. To produce a larger increase of sound pressure in wide area, we optimized the installation location of the side speakers under some legal constraints via the computer simulation. The simulation was conducted for the sound frequency of 770 Hz and 960 Hz with the FDTD method. As a result of the simple line search, the optimal installation location was 0.5 meters back from the front. By comparing the sound pressure level for four-speakers sounding with that for two-speakers sounding, we confirmed that the sound pressure effectively increases around the body side.