Acoustic Mapping

I gripped the plastic collar stay and tapped its rigid tapered tip against the base of the hollow umbrella stand. A sharp, metallic ring resonated through the pine shelf, sending subtle vibrations into my boot soles. By shifting my strike angle across the curved exterior wall, the pitch rose slightly, confirming varying wall thickness and an empty interior cavity. I pressed my gloved palm flat against the cool metal to dampen the hum, timing how long the resonance took to fully decay. The hollow vessel can serve as an acoustic amplifier for detecting movement across the door threshold.