Volumetric Sound Absorber for Production Workshops with Increased Noise Level

Noise is one of the harmful production factors that negatively affect human health and operability. It also causes acoustic contamination of residential areas near industrial plants with increased noise levels. Currently, a vast number of technical means and methods to reduce production noise are available. Production and process equipment structures are under improvement in order to reduce noise radiation; innovative means to block the transmission of sound energy along the paths of airborne noise are under development. An original structure of a volumetric sound absorber with a combined resonator element integrated into the porous sound-absorbing material has been discussed in the article. The resonator element consists of a set of acoustic quarter-wave resonators and the Helmholtz resonator chamber. It is possible to adjust the volume of resonator chambers, which allows for a precise frequency adjustment of efficient functioning of sound absorber at the dominant frequency of the sound field generated by operating machinery of the production workshop. Sound waves are absorbed within the high-frequency range of the sound spectrum due to the physical process of dissipating dispersion of sound energy in the structure of porous sound-absorbing material with a high sound-absorbing coefficient within the frequency range of 800–10,000 Hz. At the same time, sound waves at the discrete frequencies of noise radiation from production and process equipment within the range of 100–500 Hz will be absorbed by a combined resonator element tuned for the sound frequencies required for absorption. The results of experimental measurements of sound levels in a test anechoic chamber with installed volumetric sound absorbers have been provided; the sound level decrease from 3 to 16 dBA within the frequency range 315–10,000 Hz (compared to the option without sound absorbers) has been registered.