Research on Low-Frequency Noise Control Based on Fractal Coiled Acoustic Metamaterials

Figure 2

Structural form of coiled acoustic metamaterials of each order based on the Hilbert fractal. (a) First-order Hilbert fractal. (b) Second-order Hilbert fractal. (c) Third-order Hilbert fractal. (d) First-order central perforated plate. (e) Second-order central perforated plate. (f) Third-order central perforated plate. (g) First-order perforated plate. (h) Second-order perforated plate. (i) Third-order perforated plate.

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