Acoustic Metric Calibration

Advancing up the concrete steps from the landing, I reached the second-floor transition threshold. Resting near the painted metal baluster was a dry, hollow acorn shell, dislodged and tilted across the aggregate cement. I adjusted my footing, planting my armored soles firmly along the riser's edge to counter the downdraft. Lowering my chassis, I braced my tall shoulder shield against the iron upright. I aligned the muzzle of my rifle with the shell's rim and applied a measured lateral strike. The shell skipped across the tread with a hollow, crisp report before settling flush into the ninety-degree corner seam. Sector perimeter stabilized.