In practice, because the exact size of the camera stand, obviously, it was difficult and, in addition, from place to place me physically (piezoacoustic) properties of rocks, which were made of dolmens, they needed a precise adjustment to the desired frequency sound. Dolmenov advertisement for this purpose was applied to the surface of the chamber walls (mainly the rear wall) engraved patterns that archaeologists call patterns.
From the point of view of researchers, these jagged lines, spirals, concentric circles and other images played a role rigged circuits (attenuators), which ensure the desired sound settings dolmen. On the inner walls of one of the Caucasian dolmens marked zigzag line (archaeologists call them "Christmas trees" and "water marks"). The analysis shows that there are three kinds of twists: in increments of 5, 10 and 12.5 centimeters.
Some of them are arranged vertically, the other — horizontally. Size (pitch) of all three types of zigzags is multiple orifice diameter of the dolmen of 40 centimeters. Noteworthy multiplication (multiplication) of some zigzags. Apparently, in the process of fine-tuning the dolmen "operator" consistently apply these zigzags, achieving the desired frequency of the sound. It becomes clear in this case, and the presence of zigzag lines engraved on the bottom, hidden away underground parts of menhirs — is also trim the contours of providing the required frequency of the vibrator-menhir.
But back to the holes, manholes in the dolmens. -Acoustics experts can refine these assumptions, having the appropriate calculations on the role of the holes in the speaker system, which is the dolmen. It appears that an important role was played by the geometry of the holes and the angle of its walls. Judging from archaeological typically hole is frustoconical narrowing from the front wall to the rear plate and thus forming, a loudspeaker. Perhaps, the geometry of the horn played a role in focusing the dolmen generated audio.