Normal-incidence acoustic data for perforated plates with stepwise apertures backed by TPMS cores

This Data Descriptor presents normal-incidence acoustic measurements of thirty-two specimen configurations combining perforated plates having stepwise apertures with sheet-type triply periodic minimal surface cores. Eight perforated face-sheets, differing in aperture diameter and in the axial length of each aperture section, were each measured with an empty backing cavity and with cores of Schwarz Primitive, Gyroid and Diamond topology. Measurements were made by the two-microphone transfer function method in a 100 mm impedance tube from 50 Hz to 1600 Hz at 2 Hz resolution, with three acquisitions per configuration. For every configuration the dataset provides the sound absorption coefficient and the complex reflection coefficient, normalised surface impedance and normalised surface admittance, as individual repeats and as their mean, together with the unmodified instrument exports. The three core geometries are deposited as STL models, and all tabulated core parameters were measured from those models rather than taken from design targets. Repeatability, internal consistency, the recommended frequency range and the known limitations of the specimens and the measurement are documented.