Additive manufacturing (AM) has enabled the realization of complex, high-performance acoustic metamaterials. However, bridging the gap between idealized numerical performance and physical reality remains an ongoing engineering challenge. This research investigates the effects of four AM technologies (fused deposition modeling [FDM], stereolithography, digital light processing [DLP], selective laser sintering [SLS]) on the acoustic performance of a specialized acoustic metamaterial (AMM). While numerical models in COMSOL Multiphysics provide idealized benchmarks for sound absorption coefficient (SAC) and sound transmission loss (STL), this study demonstrates that the physical manufacturing process introduces critical deviations. Experimental results reveal that for SAC, DLP provided the highest fidelity due to its superior surface finish and sharp geometric definition. In contrast, FDM samples showed significant SAC deviations, where inherent process limitations increased thermoviscous losses, leading to higher-than-predicted absorption. However, an inverse trend was observed for STL. The ability of FDM to produce a monolithic structure resulted in STL values that closely aligned with numerical predictions. Conversely, the high-precision DLP and SLS methods required subassembly joining, where microscopic interstitial leakages caused a sharp degradation in STL performance. The findings indicate that these leakages often appear as absorption in SAC measurements, hiding structural failures that only become evident during STL characterization. This study concludes that for industrial noise mitigation applications, the necessity of monolithic construction and the elimination of acoustic leaks outweigh the benefits of high-resolution surface finishes. These results provide a vital framework for selecting AM processes based on the specific acoustic requirements of the design.