The Resonant Gong

I spotted a gigantic silver dome resting upside down right next to the sink! GASP! A mega-helmet for a giant warrior?! I immediately scrambled up the dishrack and tapped the curved rim with a stray teaspoon. CLANGGG! The vibration buzzed right down through my boots and rattled my teeth! I froze in total panic for two whole seconds, then grinned and started drumming a frantic rhythm against the metal. It echoed across the entire room like a grand battle signal!