Cave paintings and the famous Stonehenge structure may have been inspired by the behavior of sound waves, which at the time were misinterpreted as being supernatural.
Everyone is familiar with the concept of an echo, which can make it seems as if a bodiless voice is answering your call. This phenomenon is really caused by sound waves reflecting off a surface, but may have seemed much stranger before we had this explanation, the Acoustical Society of America reported.
"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," said Steven J. Waller, of Rock Art Acoustics.
The researchers noted sounds of clapping hands can sound like hoof beats, and multiple echoes within a cavern can cause a monstrous reverberation comparable to a stampede.
"Many ancient cultures attributed thunder in the sky to 'hoofed thunder gods,' so it makes sense that the reverberation within the caves was interpreted as thunder and inspired paintings of those same hoofed thunder gods on cave walls," Waller said. "This theory is supported by acoustic measurements, which show statistically significant correspondence between the rock art sites and locations with the strongest sound reflection."
Waller also noticed similarities between an interference pattern and Stonehenge. To test this the researcher set up an interference pattern in a large open field with two flutes "droning the same note." Participants were blindfolded and asked to listen to the sound, and the high pressure from one flute proved to cancel out the low pressure in the other creating the illusion of rocks casting "acoustic shadows."
"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," Waller said.
The findings suggest acoustical phenomena were significant in early cultures and the natural soundscapes of archaeological sites should be carefully preserved.
The findings will be presented at the 168th Meeting of the Acoustical Society of America (ASA).
