Recently we studied the acoustic properties of the underground Ħal Saflieni Hypogeum in Malta. Identified as “architecture in the negative”, it is a unique prehistoric complex, intentionally sculpted with features that mirror megalithic temples above ground. It is known that the Hypogeum was used in the Neolithic not only as a depository for bones, but also as a shrine for ritual use. In a room known as the “Oracle Room” set in the second level of the hypogeum, we have been able to detect the presence of a strong resonance effect: a double resonance frequency at 70Hz and 114Hz. With a male voice tuned to these frequencies it is possible to stimulate the resonance phenomenon throughout the hypogeum. It was further detected that percussion instruments can stimulate the resonance by their harmonics. Laboratory testing indicates that these frequencies have a strong effect on human brain activity. Since it is likely that the chambers served as centers for social or spiritual events, the resonance of the chamber cavities would have supported human ritual chanting and mystic consciousness.
