The Third Frequency Range of the Sound Insulation Plot of the Single-Layer Partitions

Abstract

The main concepts of sound insulation theory of the massive plates were developed in the mid-20th-century. There were obtained the frequency dependence of sound insulation from the plate mass and the plate stiffness [1, 2]. The multiple researches on dependence of insulation from sound incidence angle [1, 2, 3, 4] and coefficients of internal friction for plates materials were carried out [1, 2, 3, 4]. The comparison of theoretical and experimental results showed the generally statistical matching, but in the same time, there were frequently observed their considerable differences [1, 2].There was a necessity in additional studies in that period. Due to the electronics development and perfect appliances on its base, the observational researches begun to prevail, such as in issues [5, 6, 7, 8, 9, 10]. Thereafter, the reference curves with the three frequency ranges for sound isolation calculation were obtained, due to the large mass of experimental data processing. The first two ranges are divided by the wave coincidence frequency, and the third one limits the maximum possible insulation irrespective of frequency.The articles [11, 12, 13] show, that the existing formulas of sound propagation through the interface of two media and the flat layers, which are developed from the continuity conditions, mismatch to these conditions on all incident angles, except of the normal. So the present insulation theories, which are depending from the sound incident angle, make no sense.The issue [14] shows, that the calculation sound insulation method, which is based on discrete (concentrated) models of sound propagation with the application of momentum conservation law and the kinetic energy for the plates with the mass more than 50kg/m2, gives the more exact results of comparison with the experimental data [15, 16], than with the calculation data by the standard curve. The contributions [15, 16] contains the evidences about the sound insulation values mainly in first two frequency ranges. The third frequency range is become beyond the limits of measurements. This article contains the results of publication materials, involving the sound insulation data at the third frequency range.