A特性音圧レベルの最大値を用いた床衝撃音評価

心理評価に基づく補正方法の検討

抄録

 In buildings such as condominiums and hotels, the sound insulation performance of floor impact sounds has been of great importance. For the provider of buildings, it is important to quantify the sound insulation performance of floor impact sounds of buildings in comparable methods. Existing evaluation methods using standardized floor impact sources have been developed mainly to achieve this objective. On the other hand, it is important for the occupants how they feel psychologically for the floor impact sound itself.

 It was pointed out that the existing evaluation methods using the L-curve defined in the Japanese Industrial Standards (JIS) did not always correspond well to psychological ratings. Therefore, the maximum sound level with ‘A’ frequency weighting and ‘Fast’ time weighting (L_AFmax) was proposed as an alternative physical index in the past studies. In those studies, the heavy and the light floor impact sounds were separately investigated according to the measurement methods defined in the JIS, but such categorization is not indispensable in psychological evaluation of floor impact sound itself.

 In the present study, a psychological evaluation test was carried out using floor impact sounds modeled by a simple way, just varying peak frequencies, rather than focusing on the heavy and light categorization of floor impact sounds. The listeners were instructed to imagine that they are in a living room, and they evaluated the degree of distracting depending on environmental sounds containing floor impact sounds while reading a short story. The results showed that the degree of distracting was different even when L_AFmax of the floor impact sounds was aligned, and the degree of distracting was higher for the floor impact sounds with low frequency components such as 63 Hz and 125 Hz octave bands. Furthermore, comparison of the degree of distracting with other physical indices proposed in previous studies showed that the total exposure to sounds may correspond better to the degree of distracting than the maximum sound pressure level. Based on these results, we proposed the integrated time-varying loudness (N_int), and N_int was corresponded better to the degree of distracting than the other physical indices. We also proposed a method to correct L_AFmax by using the center frequency of the band which mainly determines L_AFmax so that it uniquely corresponds to N_int. This correction method was effective for a part of the floor impact sounds used in this study. Whether this method can be applied to other floor impact sounds is a subject for further study.