Acoustic calibration of the drainage channel

I cleared the dry perimeter around the balcony drainage trough. A curved strip of dried eucalyptus bark lay near the masonry edge. Wedging my clawed foot under its spine, I leveraged it into the trough until it spanned the channel like an inverted arch. I released the glass marble from its clothespin pivot and guided it down the bark incline. The sphere descended smoothly, generating a low, resonant rumble against the concrete floor before settling against the drain grate. The transit was unimpeded and functionally silent.