RESEARCH ON THE EFFECTIVENESS OF THIN NOISE BARRIERS IN CONFINED SPACES

Abstract

The possibilities of using thin noise barriers to reduce acoustic impact on workers and the population in confined spaces have been investigated. Such conditions are typical for construction noise when working in densely built-up areas. The most convenient mathematical apparatus for predicting the effectiveness of an acoustic screen is presented. The measured amplitudefrequency characteristics of noise reduction indices depending on the area of the acoustic screen are given. An acceptable convergence of calculated and experimental data has been established. It has been established that thin screens are insufficiently effective in the low-frequency part of the sound spectrum. The influence of openings in the protective structure on noise reduction indices has been investigated. It has been established that at medium and high frequencies, openings become critical for noise protection. At the same time, at low frequencies, they have practically no effect on the effectiveness of the screen. Noise reduction indices in octave frequency bands and their changes with distance from the screen to the sound receiver were measured. It was found that at low frequencies, sound levels can increase (negative indices) due to interference phenomena. It is proposed to give screens resonant properties in confined spaces. It is advisable to choose the sound frequency with the maximum amplitude as the resonant frequency. To increase the effectiveness of the screen in the mid and high frequency ranges, it is advisable to manufacture two-layer panels and fill the gap between the layers with noise-absorbing porous material.