From Mount Sinai to the Oracle at Delphi, the history of religion is filled with examples of "special places" where ancient peoples could receive messages from their gods. But could acoustic theory provide clues about the way sound and geology combined to influence how religions developed? Dr. Stephen Waller suggests that this may be the case.
In a presentation given at the 168th meeting of the Acoustical Society of America (ASA) being held in Indianopolis from October 27-31, Waller has proposed that the complex acoustical properties linked to caves and other important locations around the world may have inspired some of the earliest examples of religious art. A researcher at the Rock Art Acoustics laboratory in La Mesa, California, Stephen Waller is an authority in archaeoacoustics, or the study of the acoustics of archaeological sites and how they may have influenced the ancient peoples who lived there. As part of his research, he has examined the acoustic properties of rock art sites around the world including the cave art at Altamira in Spain.
"Ancient mythology explained echoes from the mouths of caves as replies from spirits, so our ancestors may have made cave paintings in response to these echoes and their belief that echo spirits inhabited rocky places such as caves or canyons," Waller said in his presentation. Thunder and lightning was often linked to thunder gods whose voice was reflected from caves and other places with unusual echoes. "This theory is supported by acoustic measurements, which show statistically significant correspondence between the rock art sites and locations with the strongest sound reflection," he added.
Using careful sound measurements, Waller demonstrates that, just as light can be reflected to provide the illusion of seeing yourself in a mirror or a pool of water, sound waves reflecting off a surface can appear to be coming from a virtual sound source behind a surface reflecting that sound. “This can result in an auditory illusion of somebody answering you from within the rock,” Waller said. Structures such as Stonehenge can also create an interference pattern giving them a "mystical" sound. Through careful acoustic testing, he determined that Stonehenge and other megalithic stone circles radiate acoustic shadows that recreate interference patterns.
“My theory that musical interference patterns served as blueprints for megalithic stone circles — many of which are called Pipers’ Stones — is supported by ancient legends of two magic pipers who enticed maidens to dance in a circle and turned them all into stones,” he noted.
Among the hundreds of rock art sites with known acoustic properties that might have inspired religious worship are the Great Enclosure and Matobo in Zimbabwe, Africa, the Trial Harbour ringing rock in Tasmania, Australia, Pancake Stone and Swastika Stone on Ilkley Moor, U.K., Scotland's 'Clach na Choire' or 'The Ringing stone', the Petroglyphs Park in Ontario, Canada, and the Fort Ransom Writing Rock in North Dakota. This is just a partial list and Stephen Waller's site includes dozens of other examples as well as audio recordings of their acoustics.
"People didn't even know that sound was propagated by pressure waves until a few centuries ago," Waller said. "We know that sound was a great mystery to the ancients because there are many myths about echoes being a spirit that lives in the rock and which calls back, or that thunder was caused by large birds in the sky flapping their wings. They had supernatural explanations for all these sound phenomena."