STEPPED ACOUSTIC STRUCTURES WITH MULTIPLE DEGREES OF FREEDOM Russian patent published in 2019 - IPC G10K11/172 

FIELD: acoustics.

SUBSTANCE: invention relates to noise absorbing structures. Stepped acoustic structure has multiple degrees of freedom and is equipped with membrane covers. Membrane covers are located in cells of stepped honeycomb structure. Acoustic barrier is located on second side of cellular structure to form resonators. Membrane cover comprises a fastening portion for attaching the cover to the walls of the cell. Fixing section has outer edge and fastening boundary, which is at distance of fixation from outer edge of fastening section. Fixing section is connected to walls and continues parallel to them, and fixing boundary is located at specified depth of attachment in cell. Cell has first acoustic impedance. Fixation boundary of the second membrane cover is located at the second attachment depth in the second cell, wherein the second attachment depth is equal to the first attachment depth. Step is located in the second cell. Step reduces the cross-sectional area of the second cell by a value sufficient for the second cell to have a second acoustic impedance, which differs from the first acoustic impedance to impart multiple degrees of freedom to said stepped acoustic structure to reduce noise generated from the source.

EFFECT: increase in the noise suppression efficiency.

20 cl, 14 dwg