Skilled listeners can echolocate even silent objects by their sound absorption.

Evidence

Born-blind people with normal hearing don’t just hear sounds: they can hear objects (that is, have an awareness of them, chiefly through their ears) when they are fairly close at hand, provided these objects are not too low; they can also in the same way hear something of the shape of their immediate surroundings Silent objects such as lamp posts and parked cars with their engines off can be heard by me as I approach them and pass them as atmosphere-thickening occupants of space, almost certainly because of the way they absorb sound or echo back the sounds of my footsteps and other small sounds It isn’t usually necessary to make sounds oneself to have this awareness, though it helps. — Eric J. Heller, Why You Hear What You Hear- An…, 2540

Categorization

• XREF: Connects to Oliver Sacks’s The Mind’s Eye but also to the broader question of how hearing reveals the environment — echoes the book’s core theme of auditory scene analysis.
• QUESTION: The claim that passive sounds (from one’s own footsteps, ambient noise) get absorbed and echoed by nearby objects is compelling — what is the actual physical mechanism and minimum reflectivity needed?