Abstract
In this paper, taking phase in consideration, we discussed the characteristics of floor impact sound of low frequency (lower than 63 Hz band) and the calculation of its frequncy response function. We studied the characteristics by experimental modal analysis with a scale mode1 (S1:16). We have obtained the following results; (1) The sound pressure mode of the floor impact sound is determined by floor vibrathon mode and acousitic mode of lower sound field. However, the mode with lower damping ratio has large influence. (2) As for the sound radiation of a floor with fairly high mechanical impedance, the movement of the floor can be modeled as follows, -The floor is divided into smaller grids compared to the wave length of bending wave. -Each grid move in the direction vertical to the floor. -the amplitude and the phase of each grid are represented by those of the bending wave at the center of the grid. On the basis of these results, we suggested a method of practical calculation for frequncy response function of floor impact sound, and examined its accuracy.
