Sound-absorption performance of a coupled square-neck embedded Helmholtz resonator

We propose a coupled square-neck embedded Helmholtz resonator (S-NEHR) with a deep-subwavelength thickness. By precisely designing each cell peak, the average sound-absorption coefficient of the nine coupled S-NEHR structure is greater than 0.9 at 300-410 Hz, and the thickness is only 1/30 of the working wavelength. Adding a microperforated panel (MPP) in front of the coupled structure enables a smaller size and larger bandwidth (500-1000 Hz). The simulation and experimental results demonstrate that the S-NEHR structure has great application prospects in engineering noise control due to its extraordinary sound-absorption properties and compact structure. (C) 2022 The Japan Society of Applied Physics