Selection of optimal sound absorbing materials in industries and agricultural machines using acoustic simulation of fractal structure of Manger sponge

There are several ways to control noise pollution. Due to the spread of acoustic science, the use of impedance tubes and the use of sound absorbers are of particular importance. The simulation of several adsorbents is discussed in this paper. Fabric absorbers with small holes, Cavity-coated absorbers and… There are examples of these absorbers. Various factors such as material, step and frequency affect this absorber. In this study, the changes of sound level under material, step and frequency factors were studied, analyzed and compared in two experimental and simulation methods. Mainly simulation for different types of absorbers allows for better comparison and selection of the best absorber for sound control. In both experimental and simulation methods, the least changes in sound pressure level in MDF were observed. This value is reported for the experimental method of 70.3 dB and for the simulation of 76.5 dB. The smallest changes in sound level were reported in both methods at 128 Hz. The sound level changes for both methods were the same and from step one to step two sound pressure level changes increased. In laboratory method, one step of sound pressure level changes is 74.4 dB and in simulation method these changes are reported 80.4 dB. In step two, in both laboratory and simulation methods, the sound pressure level changes were 76.6 and 82.4 dB, respectively. Comparing the mean sound level changes for both ionolite and mineral wool, it is observed that in ionolite, the rate of these changes has increased from 25.9 dB to 27.8 dBfrom one to two steps, while in Mineral wool these changes have been reported in both steps with a constant value of 22.4 dB. therefore, the ionolite material can be introduced as the optimal absorber in terms of sound level changes in a wider range.