Table 1 Geometric and physical characteristics of acoustic metamaterials.

Total Diameter

D

100

mm

overall high

H

50

mm

Density of air

Po

1.172

kg/m³

Pore diameter

d_p

20

mm

d_q

11

d_r

11–13

The characteristic impedance of air

Z_o

405.7

Pa/(m/s)

Viscosity coefficient of air

η

1.85 × 10⁻⁵

Pa·s