IMPROVEMENT OF THE EFFICIENCY OF NOISE PROTECTIVE SCREENS DUE TO SOUND ABSORPTION

The object of research is the sound field from linear sound sources around noise screens. The decrease in sound levels with the screen is primarily due to the geometric dimensions of the screen and the relative position of the screen and the sound source. The influence of these factors has been given a large number of scientific publications. However, the problematic point of such studies is that screens were considered either completely acoustically rigid or sound-absorbing. In this paper, the situation of the impedance screen is considered, quite often applied in practice. The calculation of the field around such a screen is carried out by computer simulation, which makes it easy to change the value of the acoustic impedance of the screen surface. To calculate the sound field around the screen, the finite element method is chosen. Sound-absorbing properties of the screen were determined by changing the acoustic impedance of the front side of the screen. At the same time, the screen remained acoustically opaque. Thus, an analysis is made of the influence of the sound absorption coefficient on the sound field around the screen from different heights of the screen and the distance of sound sources to the screen. This makes it possible to obtain results of sound pressure levels around screens encountered in engineering activities. Studies have shown that the use of sound-absorbing cladding for noise screens can increase their effectiveness. It is revealed that the closer the screen is located to the sound source, the greater the influence of its sound-absorbing properties. It is shown that for low frequencies the increase in screen efficiency due to sound absorption can reach 5 dB. The obtained results during the study can be used in the design of noise protective shields to reduce noise levels from traffic flows. The results obtained will be especially useful when designing screens with heights of more than 4