Acoustic Characterization of Metamaterial Structures Fabricated via Foamed Filament 3D Printing

Noise pollution is one of the most widespread problems in modern society and constitutes real danger to the human health. In particular, the reduction of interior noise levels in the transportation industries remains a big problem to cope with. Commercial sound absorber materials that have high values of the sound absorption coefficient are usually porous, they exhibit good sound absorption properties in the high frequency range but little in the low and medium frequency range (250–1600 Hz). Same condition but in different range of frequency applies to the other two types of sound-absorbing systems such as resonant cavities and membrane systems. In nature, there is no material that can cover a wide range of frequencies with a good absorption value, which is why metamaterials were born. Acoustic metamaterial are artificial structures, with unconventional effective properties. In these work an attempt was made to join the trends of typical absorption coefficients of the mentioned structures into a single 3D printing sample, characterized by light and equally strong.