Ultrathin bi-directional sound obstruction channel

Abstract

The invention discloses an ultrathin bi-directional sound obstruction channel. When obstructing sound, the ultrathin bi-directional sound obstruction channel can allow electromagnetic waves, air flow or even objects to pass through. The ultrathin bi-directional sound obstruction channel includes an upper metasurface and a lower metasurface which are arranged in parallel; surfaces of the upper metasurface and the lower metasurface, which are opposite to each other, are symmetrically provided with a plurality of groups of folding structures; each folding structure includes at least five obstruction boards which are arranged side by side; cavities are formed between adjacent obstruction boards; and cross beams are alternately distributed on the obstruction boards in the cavities. According to the ultrathin bi-directional sound obstruction channel of the invention, operation and control on the direction of the wave vector of reflected waves by the upper and lower acoustic metasurface materials are simply utilized, and at the same time, the super thin characteristic and the abnormal reflection function of the metasurfaces are ingeniously utilized, and therefore, acoustic waves of which grazing incidence is along the metasurfaces geometrically, namely, acoustic waves transmitted along the axial direction of the pipeline, are deviated by an angle close to 90 degrees, and after two times of action, the direction of the wave vector of the reflected waves can be opposite to the direction of incident waves, and the acoustic waves can be effectively obstructed at a certain depth of a waveguide.

Description

technical field [0001] The invention relates to an ultra-thin sound-blocking ventilation channel realized by using an acoustic metasurface, which belongs to an acoustic device. Background technique [0002] Traditional pipeline noise reduction equipment such as the Helmholtz resonator pipeline based on resonance noise reduction is equivalent to a resistant silencer, consisting of a throat and a cavity. The air in the throat is equivalent to the sound quality, and the cavity is equivalent to the spring. It requires a larger external cavity to provide impedance mutations. When the sound wave frequency is closest to the natural frequency of the muffler, the noise reduction is the largest. In addition, the resistive muffler uses sound-absorbing materials to attenuate the sound wave energy. However, the above mechanisms are either limited by the size of the muffler being too large, or by being easily affected by the external environment and having a short life cycle. Therefore,...

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Problems solved by technology

In addition, the resistive muffler uses sound-absorbing materials to attenuate the sound wave energy

However, the above mechanisms are either limited by the large volume of the muffler, or by being easily affected by the external environment and having a short life cycle.

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