Recent excavations in the lower city of Mohenjo-Daro have identified a unique architectural feature: a sunken sound-amplification courtyard. The plaza is paved with specialized vitrified terracotta tiles laid over hollow chambers, designed to act as acoustic resonators. Preliminary tests suggest the space was engineered to project the voice of a speaker from a central dais across the entire assembly area with minimal echo.
Surrounding the courtyard, researchers found evidence of stone-carved seating tiers and a drainage system specifically designed to prevent water accumulation from dampening the acoustic chambers. This discovery challenges our understanding of Harappan social organization, suggesting that public oratory and centralized civic announcements played a more significant role in Indus Valley urban life than previously theorized.