Aspects of the present disclosure include apparatus, systems, and methods for enhancing passive stealth capabilities. Apparatus may include at least one acoustic attenuator comprising a metamaterial matrix having a plurality of cells and configured, upon at least a partial immersion in a fluid, to form an acoustic attenuation system including at least a portion of the matrix and the fluid, the acoustic attenuation system configured to acoustically attenuate acoustic signals incident on the attenuator from the fluid. At least one cell of the plurality of cells may comprise a plurality of sub-cells azimuthally arrayed about an axis of alignment, with at least one sub-cell of the plurality comprising a plurality of solid cell segments substantially oriented in alignment with a mapping geometry comprising an inversion of a canonical tangent circles mapping.
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