This crossing, between storm drains, a quiet stream and Aigburth Road is an unexpected sonic cavern. When I placed the mic inside the large concrete cylinder dead center of this environment, facing outward toward the stream, the whoosh from passing cars a block away could be heard as a slow wash of rising and falling wind. And when cars hit the sewer cap east of Donnybrook, a low thump was produced.
But the resonance was not so deafening as to drown out the natural noises in the little bramble that surrounds this overpass. A chorus of birds, crickets, passersby and squirrels can be heard distinctly from the lower frequencies (which I chose to exapand to highlight the sonic qualities of the large space and its doomlike atmosphere).
On my next outing here I'll bring the mic into the storm drain, as far back as it can go - at the crossing of multiple drains.