Science and Technology of Energetic Materials

Vol.66, No.4 (2005)Special Issue for ISEM 2005


Excess attenuation of blast sounds propagating over hilly regions and evaluation of the sounds from viewpoints of occupational health and psychological reaction
Hiroyuki Imaizumi, Yasumori Takahashi, Takehiro Isei, Eishi Kuroda, Yoshio Nakayama, Sadashige Horiguchi, and Masatake Yoshida


This study examined the Three-Straight-Line model, which was proposed by Isei et al. for the excess attenuation of blast sounds propagating over hilly regions, by using newly collected data obtained from several field measurements in areas with varied terrain. Effects of the blast sounds propagated over hilly regions were also studied by comparison with the criterion governing impulsive noises in the workplace as well as in relation to the psychological reactions of human beings to sonic booms. Excess attenuations measured up to about 2.5 km across varied hilly terrain mostly agreed with those predicted by the Three-Straight-Line model. Frequencies at which the attenuation clear appeared tended to become lower with longer range propagation, probably because the acoustic surface and acoustic ground waves of the blast sounds were more attenuated during long-range propagation over uneven terrain. Peak sound pressure levels of the blast sounds at the measuring points ranged from 110 to 160 dB, and most of the blasts were below the level of the hearing-protective criteria governing impulsive noises in the workplace, except close to the blasting point. In addition, when psychological reactions to sonic booms were compared with peak sound pressure levels of the blast sounds, those levels measured at distances of more than 1 km were classified into the categories "tolerable" or "no unpleasantness." According to these indices, the blast sounds measured in the field seemed to have only slight effects from the occupational health and psychological points of view.

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Blast, Impulsive noise, Excess attenuation, Three-Straight-Line model, Outdoor sound propagation, Hilly region, Sonic boom

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