
The builders of Stonehenge were guided by the task of reconstructing the interference pattern, says American scientist Stephen Waller.

An independent researcher believes that the location of the stones corresponds to the pattern of sound waves generated by a pair of musical instruments, that is, the regular repetition of loud and quiet sounds as a result of acoustic interference while playing the same note.
The specialist believes that it was possible to capture the ability of sound waves to amplify and extinguish each other in the Neolithic. And to the ancient man, whose thinking was conditioned by the mythological model of the world, it might seem (the scientist continues to argue) that there is an invisible object between the listener and the instruments. Mystic!
Mr. Waller equipped two flutes with an air pump to play continuously and began to walk in circles. Indeed, the sound either faded or intensified. The experiment was then repeated by blindfolded volunteers. It seemed to them that from time to time there were some obstacles between the sound source and the ear.
The researcher believes that the ancient inhabitants of Britain could dance to two bagpipes, and, as people moved in a circle, the sound in the same way faded, then intensified, as if between the musicians and the dancers at an equal distance from each other stood, say, invisible trees or stones. This effect, according to the scientist, was tried to reproduce by the builders of Stonehenge, because it could seem supernatural to ancient people - as if something from the "subtle" world made itself felt. Straight pipe at the threshold of dawn, however …
Accordingly, in the center of Stonehenge, Mr. Waller places musicians, while the participants in the ceremony had to go around the building in a circle, experiencing a certain mystical experience - probably, familiarization with the secrets of the universe, in an inexpressible other way.
Realizing perfectly well that the hypothesis looks like an ordinary speculation, Mr. Waller reinforces it by referring to local legends. Some megaliths were popularly called piper stones. They also talked about invisible towers from the air and two pipers who lured the virgins into a circle and then turned them into stones.
This is not the first suggestion that the builders of Stonehenge knew a lot about acoustics. In 2009, Rupert Till of the University of Huddersfield (UK) showed using computer analysis that drumming and chanting must have resonated from rocks.
The hypothesis was presented at a meeting of the American Association for the Advancement of Science.
Restored the sound used to frighten the faithful by the priests of Chavin de Huantar
More than three thousand years ago, people flocked to Chavin de Huantar, a high-altitude village in the valley of the Peruvian Andes, to hear the voice of the oracle. Indeed, he spoke - and this sound was restored.
At the annual meeting of the American Association for the Advancement of Science, a group of researchers presented evidence that the Chavin culture (and possibly other ancient cultures) possessed acoustic techniques that would be the envy of modern concert hall engineers.
Chavin de Huantar consists of terraces, squares, ornate megaliths and a temple. There is ample evidence that the site was used for religious purposes. Among them are bas-reliefs of powerful animals (jaguars, condors and snakes), images of hallucinogenic plants and finds of tools with which the latter were prepared for use.
Part of the interior architecture is an intricate multi-level labyrinth with acoustically influencing long corridors and staircases well preserved enough to understand what ancient people heard. Moreover, shell pipes have been excavated in the village. Apparently, they were dummy, which was demonstrated at the conference by Miriam Kolar from Stanford University (USA).
In the 1970s, a Peruvian archaeologist discovered a grand canal at the Chavin de Huantar with built-in terraces. He suggested that this whole structure was intended to amplify the sound of rushing water. Ms Kolar and her colleagues suspect that another part of the Chavin de Huantar was designed and built to create sound effects. The long and narrow central aisle gradually narrowed, as a result of which the terrible sound of the trumpet blown into the inside of the temple was perfectly heard before the public gathered in the open air.
If the listeners were in different places in the labyrinth-like corridors of the temple, then the repeated amplified echo completely hid the source of the sound and added supernatural sensations.
One way or another, it is obvious that the Chavin de Huantar complex was built specifically for acoustic effects.