ゴムボールを衝撃源とした最大A特性床衝撃音レベルの予測方法の検討

Abstract

The conventional method of evaluating floor impact sound is by comparing measured octave band impact sound pressure levels with the rating curves, and a small automobile tire is used as the impact source. However, it is expected that rubber balls will be widely used as an impact source, and A-weighted maximum sound pressure levels will be one of the evaluation values for the floor impact sound. The purpose of this study is to develop a method of predicting A-weighted maximum sound pressure levels for heavy impact sounds by a rubber ball. In the prediction method, the vibration characteristics of concrete slabs are calculated using the finite-element method. Then the impact sound levels are estimated from the impact force of the rubber ball, the calculated vibration characteristics of the slab, and the acoustic characteristics of the receiving room using the statistical energy theory with some approximations at low frequencies in consideration of wave theory. The frequency range and frequency bandwidth in the calculation process were determined from extensive impact sound data measurements in some buildings. Calculation and measurement results for buildings show the developed method can precisely predict the A-weighted maximum sound pressure levels for heavy impact sounds by a rubber ball. Using the investigated method, the calculated results agreed well with measured values.