More than 3 millennia ago, people came to Chavin de Huantar, a village in a high valley in the Peruvian Andes, to hear the oracles speak - in the voice of resonant conch shell trumpets, with the help of some clever architectural design.
     Chavin de Huantar consists of terraces, squares, ornate megaliths, and a temple, and there is abundant evidence that it was used for religious ceremonies. The site also contains bas-relief sculptures featuring animal imagery - jaguars, condors, and snakes - along with images of hallucinogenic plants and the tools used to prepare them for consumption.
     Chavin de Huantar is particularly well suited to the study of ancient uses of sound, says Miriam Kolar, an archaeo-acoustics researcher at Stanford University in Palo Alto, California. The interior contains elaborate, multilevel mazes with long corridors and staircases that are well enough preserved to detect what the original residents must have heard. Moreover, ancient conch shell trumpets have been excavated in the village, and fossil conch shells are embedded in stones on the floor of the temple.
     In the 1970s, a Peruvian archeologist identified a large canal at Chavin de Huantar with built-in terraces, which he proposed were designed to create sound from water rushing over edge. Kolar and her colleagues suspected that other parts of the site might have been intended to create certain sound effects. Sure enough, a long, narrow central passage grew narrower, a design that ensured that the sound of conch shell trumpets -  called pututus - propagates from the interior of the temple to the outside.
     "[Kolar] has good evidence to show that [the acoustic design] was purposefully done, says Steven Waller, an independent scholar in La Mesa, California, who has investigated the acoustics of ancient ceremonial caves, and who presented evidence at the session showing that Stonehenge and other stone circles in the British Isles were designed with acoustics in mind. "We should preserve soundscapes of these sites in case they're important."

Edited from Science Now (16 February 2012)