Building balconies accidentally form corner retroreflectors that echo sound back to a speaker

Evidence

Sometimes the exterior of buildings will have balconies or other structures that (accidentally) form excellent retroreflectors. The late Professor Frank Crawford of the Physics Department at Berkeley noticed this on the exterior balconies of Latimer Hall on the Berkeley campus. The balconies returned an excellent echo to the sender from a range of different directions. — Eric J. Heller, Why You Hear What You Hear- An…, 213

Categorization

• SEED: An accessible essay angle: ‘why your voice echoes off apartment buildings’ — everyday urban retroreflection, from balconies to street fixtures.