Combination of a 3D-printed microperforated panel and a Helmholtz resonators array for low-frequency sound absorption

The application of solutions based on conventional porous materials for low-frequency sound absorption is often limited to the available space for their installation, as these require a significant thickness to be efficient. A system combining of a microperforated panel with an array of Helmholtz resonators, properly designed, can provide effective noise absorption at low- and mid-frequencies with a limited thickness. In this work, the sound absorption coefficient of several systems of this type was assessed by analytical calculations, numerical simulations and experiments carried out in an impedance tube according to the standard ISO 10534-1:1996. The prototypes were 3-D printed using recycled materials. The absorption coefficient, analytically obtained, was significantly higher than that measured. However, the results from numerical simulations are in good agreement with measurements, showing that the numerical model carried out can be used for further studies to optimize the system design. An example is given by increasing of the number of Helmholtz resonators in the array, that yields an increase in the sound absorption. Results show the potential of this type of solutions to be used for low-frequency noise absorption in applications where the available space is limited.