A method for calculating the absorption coefficient of a multi-layer absorbent using the electro-acoustic analogy

A theoretical method for calculating the absorption coefficient of the multi-layer absorbers composed of perforated plates, airspaces and porous materials is proposed. Initially, for multi-layer absorbers composed either of perforated plates and airspaces or perforated plates and porous materials, the acoustic impedance is calculated using an electro-acoustic analogy. Then, for multi-layer absorbers composed of perforated plates, airspaces and porous materials, the acoustic impedance is calculated using an iterative method. Finally, theoretical calculations for the absorption coefficient of three types of multi-layer absorbers composed of different materials and including perforated plates are carried out. The results are validated by experimental results.