Fig. 9: Absorption maps as a function of the angle of incidence.
From: Sierpiński carpet-inspired hierarchical patterning of porous materials for sound absorption
a–d Maps of the absorption coefficient in the (f, \(\theta\))-plane for all the considered HLs, i.e., 0th−3rd. e–g Comparison of the absorption coefficient maps presented above reported as α3 − α2, α2 − α1, and α1 − α0.
