On the Comparative Effect of Snowfall, Accumulation, and Density on Speech Intelligibility

Sound is known to be altered in some manner by the acoustic characteristics of snow. However, the specific characteristics of snow, which actually affects the acoustical transfer characteristics, are not clearly understood. This transfer characteristics will be crucial in disaster prevention radio broadcasting systems that warn citizens working outdoors of potential natural disasters during the winter in regions with heavy snow. These systems use extremely high-output horn speakers to convey the warning messages to a large area. Accordingly, the purpose of this research is to clarify how the speech intelligibility will be influenced by the amount of snowfall, its accumulation, and the snow density. In this research, impulse response measurement outdoors is actually carried out during snowfall. We measured and compiled the transfer characteristics under several snow conditions, convolved these with test speech in order to simulate the transmitted speech quality during snow. We conducted a Japanese speech intelligibility test using these speech samples, and clarify the effect of each snow quality measure using multivariate analysis. As a result, it was found that although there is some influence of the amount of snowfall and density, the influence of the amount of snowfall becomes dominant as the distance between the loudspeaker and the listener (microphone) becomes large.