The acoustic measurements indicate that the studied sacred sites have a distinct acoustic character. Steep and rocky canyon lakes give rise to several echoes, especially in the summer. Throughout the year, the strongest and most pronounced echoes are reflected from the painted or sacrificial cliffs, which, in addition to true echoes, are reflective enough to create flutter-type echoes, auditory illusions as well as phantom sound sources. These results, together with previously unnoticed drumming figures in the Värikallio painting, provide a clue to the significance of the sound rituals at the sacred sites. This type of acoustics would have offered favourable prerequisites for ritual communications with the cliffs or with the spirits thought to dwell within them.
When reproducing the excitation signal at the foot of the sacred cliffs, the sound is forcibly reflected. This reflection or echo is heard with the ear and seen in the sound analysis plots, where it seems to repeat the excitation signal fairly accurately. In the sound pressure level plots, the spike representing the echo (e) is high and simple, which indicates that the sound is loud and structurally similar to the given signal (s).
Arrival time differences between the microphones demonstrate that this strongest echo arrives from the direction of the painted or sacrificial cliffs, or more precisely, from these specific cliffs. In the field, the direction is also clearly observable with the ear. In the map (on the left), the arrow shows the calculated angle of arrival and distance of the echo at a measurement point, whereas the red line denotes the location of the Värikallio cliff.
At Värikallio, the angle-of-arrival calculation demonstrates that the echo arrives from the level of the paintings, which lie 0.2–2.5 m above the surface of the water. According to our subjective auditory observations, the sound appears to emanate directly from the painted figures as if they were talking or answering back. In the still picture of the 3D model (on the left), the arrow shows the calculated angle of arrival of the echo in a vertical plane.
Unexpected but important evidence for the significance of sound rituals in the context of the rock paintings was discovered, when the Värikallio painting was re-documented using digital photography and the CPED toolset developed by the South African photographer and software engineer Kevin Crause. The enhanced images make it possible to identify several previously unrecognized human figures that appear to be beating a drum. The drumming figures hold a round object in one hand, while the other hand is raised in a striking position. Stylistically similar drumming figures are depicted, for example, on Sámi shaman drums of the historical period.
Hollman, J. C. & Crause, K. 2011. Digital imaging and the revelation of ‘hidden’ rock art: Vaalekop Shelter, KwaZulu-Natal. Southern African Humanities 23: 55–76.