The acoustic characterization of innovative materials is widely documented in the literature; however, it poses significant challenges for traditional methods, which often require large-scale samples. For metamaterials, this requirement results in high prototyping costs when using additive manufacturing. This thesis work is dedicated to characterizing the acoustic absorption of a labyrinthine metamaterial panel. The design of the panel is based on the integration of space-coiling unit cells of various dimensions, specifically engineered to increase the effective path of the sound wave and maximize acoustic energy dissipation into heat within the channels. The material response was investigated through an experimental measurement campaign in anechoic chambers at two different laboratories (KTH Royal Institute of Technology in Stockholm and Politecnico di Torino), adopting the two-microphone in situ measurement method to determine the absorption coefficient under specific incidence conditions.