Low-frequency sound absorption of a metamaterial with symmetrical-coiled-up spaces

• Published in: Applied acoustics Vol. 172; p. 107593
• Main Authors: Almeida, Gildean do N., Vergara, Erasmo F., Barbosa, Leandro R., Brum, Ricardo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-01-2021
• Subjects: Acoustic metamaterial; Low-frequency sound absorption; Subwavelength absorber; Symmetrical labyrinth; Subwavelength absorber; Acoustic metamaterial; Symmetrical labyrinth; Low-frequency sound absorption
• ISSN: 0003-682X; 1872-910X
• DOI: 10.1016/j.apacoust.2020.107593

A theoretical, numerical and experimental investigation of a low-frequency acoustic absorber (100–600 Hz) is reported herein. The acoustic metamaterial is based on a micro-perforated panel coupled to a multi-cavity of coiled-up spaces that is similar to a symmetrical labyrinth. On considering the visco-thermal losses, the effect of increasing the number of symmetrically coiled-up spaces that determines the peak position of the sound absorption and allows a greater sound energy absorption is discussed theoretically and proven through numerical analysis (FEM). Prototypes were manufactured using 3D printing technology and evaluated in an impedance tube. The results for the sound absorption coefficient acquired in the desired frequency range were greater than 91% with relative bandwidth above 35%, in agreement with the analytical model. Therefore, it is demonstrated that the proposed absorber presents a scale of deep-subwavelength since its total thickness is 0.033λ.