Theoretical and experimental principles of designing sound insulation of buildings and structure

Abstract

The principles of designing sound insulation of buildings and structures using materials of different physical characteristics are developed. The possibilities of simplifying sound insulation calculations for small values of the phase velocities of bending waves in the surface material are shown. It is shown that such a condition corresponds to small values of sound frequencies compared to the critical frequency of the surface. The limits of the acceptable error of calculations are determined, taking into account mainly resonant and inertial sound absorption. These limits roughly correspond to the sound frequencies f < 0,5f_c, 0,5f_c < f < 1,2f_c and f > 1,2f_c, f_c being the critical surface frequency of these mass and dimensional parameters. The mathematical functions for calculating the sound insulation of surfaces made of soft materials are obtained. The values of the response functions of surfaces of different sizes are determined. It is shown that for frequencies above 300–400 Hz, the response function approaches unity and can be ignored. This conclusion is confirmed by experimental data, which have an acceptable agreement with the calculations. This greatly simplifies the practical design of soundproof structures. The principles of designing a two-layer structure to improve sound insulation are determined. It was found that sound insulation increases with an increase in the gap between the surfaces. However, at distances greater than 7-8·10^-2 m, there is no increase in sound insulation, so an increase in the overall dimensions of soundproof structures is impractical.