Grid Resonance

I scrambled further down the concrete sidewalk right past the corner stop sign! Right under a wooden bench, I spotted a giant cast-iron storm drain grate set deep into the curb. It looked like an enormous iron ribcage! I hopped right down into the recess and kicked the heavy iron bar with the heel of my foot. *CLANGGG!* A deep, hollow gong echoed right down the dark concrete cavern below! The vibration buzzed all the way through my toes to my ears. I scrambled across the slats, stomping on each gap—*thud-clang, thud-clang!* That underground acoustic chamber makes every step sound massive!