Researchers detected the presence of a strong double resonance frequency at 70Hz and 114Hz inside a 5,000-years-old mortuary temple on the Mediterranean island of Malta. The Ħal Saflieni Hypogeum is an underground complex created in the Neolithic (New Stone Age) period as a depository for bones and a shrine for ritual use. A chamber known as "The Oracle Room" has a fabled reputation for exceptional sound behavior.
During testing, a deep male voice tuned to these frequencies stimulated a resonance phenomenon throughout the hypogeum, creating bone-chilling effects. It was reported that sounds echoed for up to 8 seconds. Archaeologist Fernando Coimbra said that he felt the sound crossing his body at high speed, leaving a sensation of relaxation. When it was repeated, the sensation returned and he also had the illusion that the sound was reflected from his body to the ancient red ochre paintings on the walls. One can only imagine the experience in antiquity: standing in what must have been somewhat odorous dark and listening to ritual chant while low light flickered over the bones of one's departed loved ones."
http://phys.org/wire-news/164386603/ancient-man-used-super-acoustics-to-alter-consciousness-and-spe.html
http://www.archaeoacoustics.org/
