The multiple nearly perfect sound absorption peaks in a wide frequency band were obtained. The design rule of the resonator, aperture and length of the embedded hole has much influence on the sound absorption characteristics of the metamaterials. We designed/proposed kinds of new-parallel connection of the Helmholtz resonator with embedded apertures. Standard acoustic power measurement shows its superior noise reduction performance over conventional porous materials of the same thickness. As an example, we demonstrate its use on a commercial kitchen hood. The structural simplicity and low-frequency absorption property allow the extended tube acoustic metamaterials to be utilized in scenarios where installation space for acoustic absorption materials is constrained. Then, two cost-effective samples are fabricated and tested using the impedance tube where good accuracy between the prediction and measurement is found. For the tube in which the viscothermal effect can not be ignored, an equivalent fluid model is used to characterize its acoustic property and end corrections are introduced to take into account the flow distortion effect at the two ends. First, an impedance model for a single-layer extended tube structure is developed using the equivalent circuit method. The metas-tructure consists of an array of units, each featuring a thin tube protruding from a perforation into a backing cavity to form a Helmholtz resonator. In this work, acoustic metamaterials based on the concept of extended tube are investigated. The sound absorption coefficient is greater than 0.87 at 488–712 Hz. On this basis, a multi-Helmholtz resonance structure is designed to achieve high sound absorption effect. The acoustic siphon phenomenon of partial MPP is discussed. The sound absorption performance of the multi-partial MPP structure has also been theoretically verified. The theory of calculating the partial MPP, which is accurate for fast prediction of sound absorption peaks, is proposed. The sound absorption peak of the MPP structure which occupies half of the total area is 0.89 at 980 Hz. In the parallel structure of partial MPP and the cavity, the MPP structure occupying three-quarters of the total area makes perfect sound absorption at 1076 Hz. The results show that the three kinds of curves, that is, theoretical and simulation and experimental curves, are in good agreement. The structure was studied by the transfer matrix method, finite element simulation and experimental test. Its purpose is to improve the sound absorption performance of the MPP in certain frequency bands. Partial microperforated panel (MPP) structures have been proposed for MPP with low sound absorption properties.
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