Long-Term Measurements of Sound Refraction Paths over Residential Areas Using Emergency Public Address Systems

摘要

Japan hosts several outdoor emergency public address systems for disaster prevention that use a radio system consisting of a master station in a local government office and numerous slave stations in the respective town. Roughly 500 m apart, the outdoor loudspeaker slave stations produce the same contents at a prescribed time every day for the purposes of maintenance. To examine the long-term measurements of test sounds in several residential areas in Tokyo, we calculated the sound propagation times for the several slave stations from cross-correlations between radio wave signals from a master station and sound pressure signals at numerous monitoring points. We also measured sound refraction paths over two-story houses in residential areas and compared results in different meteorological conditions with calculations determined with the Harmonoise prediction model.