Acoustic studies at the 3,200-year-old Andean ceremonial complex of Chavín de Huántar demonstrate that its underground stone labyrinths were engineered to automatically tune conch shell trumpets and distort human voices into roars. Researchers suggest the complex acted as a calculated neurological machine designed to terrify visitors into obedience, complicating the neat historical narrative that early Andean societies grew solely through gentle diplomacy and crop sharing.