Sound absorption of slit resonator with embedded aperture in linear and nonlinear regimes

This paper presents a slit resonator with embedded aperture (SREA) by embedding the slit-type neck into the cavity, and investigates its sound absorption characteristics in linear and nonlinear regimes. The theoretical acoustic impedance model of the SREA is established through transfer matrix method. The theoretical, simulation and experimental results demonstrate that the SREA enhances oscillating mass without altering acoustic capacity through the embedded slit-type neck, enabling it to achieve quasi-perfect absorption at lower frequencies with the same external geometry as traditional slit resonator. The formation and shielding of acoustic vortex caused by the high sound intensity increase the normalized acoustic resistance and decreases the acoustic reactance, causing the peak sound absorption coefficient to decline. This paper introduces a nonlinear correction expression for the normalized acoustic resistance of SREA by analogy with cylindrical neck.