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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.