At the end of the Stone Age (c. 4000-2000 BC in Europe), megalithic structures were erected, most of which stand to this day. In addition to earthen platforms, single megaliths and their complexes, for example, Stonehenge, built in the form of a circle, many were made in the form of earthen chambers, sometimes lined with stone, with one or more corridors for access from outside, often cruciform.
And although only bones were found in them, it cannot be argued that the buildings served exclusively as burial places - these could also be altars for sacrifices, where the spirits of ancestors were worshiped.
Acoustic archeology as a science has emerged quite recently: scientists studying the acoustic properties of ancient buildings have suggested that the people who designed and built these chambers paid great attention to the resonant properties of underground rooms.
In an attempt to shed light on how these ancient structures operated, writer Paul Devereaux and Princeton University professor Robert Jahn studied the acoustic properties of a number of prehistoric underground chambers throughout the UK and Ireland.
They surveyed the Chun dolmen in Cornwall, a megalithic single-chamber burial structure dug into the ground, and Waylands Smighty in Berkshire, a long mound with a stone-laid tomb.
Chun
After that, they conducted a study of Newgrange - a large corridor tomb with a cruciform chamber, as well as two burial structures at Lough Crew, all of which are located in the Irish County of Meath.
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Loudspeakers were installed in the chamber of each megalithic structure, through which tones sounded; in this case, the frequency of the highest intensity of sound vibrations and the loudest sound was selected. The cameras resonated thanks to sound waves: the waves propagated through corridors, reflected at dead ends, and, superimposed on the way back, amplified the sound. Comparing the frequencies that produced the most powerful reverberations, the researchers were quite surprised.
Despite the fact that the buildings were significantly different in size, shape and building materials, they all resonated in a very low frequency range: 95-112 hertz, which is quite consistent with the vocal range of a human voice, at least a male baritone. The human remains found in such buildings allowed archaeologists to come to a general conclusion: the buildings were used as burial chambers.
The researchers wondered: could the resonant qualities specific to each chamber indicate that ritual chants were performed either before or during burial in the chambers? The depth and reverberation of the voice sounding at the resonant frequency of the camera is greatly enhanced; this can "create a stable impression of the presence of supernatural forces - gods or ancestral spirits."
Scientists at the University of Reading have studied the acoustic properties of the Camster Round, a Neolithic corridor tomb in Scotland, using a replica of the structure's resonance properties. And they found out: since the tomb is built like a narrow corridor leading to a round chamber, the whole structure must resonate like a bottle.
Newgrange (Ireland).
This type of resonance is observed in a Helmholtz resonator - a bottle with a neck that is blown into; the air in the bottle expands and contracts as a whole, producing sound. Scientists have found that the chamber is designed to resonate like a bottle, producing sound inside the chamber (this is much more likely than the assumption that Stone Age worshipers gathered at the entrance to the chamber and diligently blew inside).
The model executed on a certain scale showed that the resonance inside the building should be 4–5 hertz. But wait a minute! This is far below the range of the human voice and, for that matter, the range of the key of musical instruments. People don't even hear sounds below 20 hertz. Has the coherent theory that, in the Stone Age, religious songs during rituals caused the Camster Round chamber to resonate, crumbled to pieces?
But scientists didn't think so. In their opinion, there must be a way that allows you to build up sound vibrations even at such low frequencies. Pure tone consists of pressure fluctuations, which are not picked up by our ear as sound. It is only when vibrations follow one another continuously that our eardrums vibrate at a rate of more than twenty times per second, and we distinguish the note.
But when you hit the drum at a speed of four to five times per second, audible sounds will occur, repeating at a frequency of 4-5 hertz. Each beat produces sonic waveforms (like the vibrations that make up a pure tone), but the beat is followed by the reverberation of the drum's skin - we can hear it.
Stony Littleton is a Neolithic mound found in Somerset. What if he was acting on the principle of a resonating chamber, which made religious chants more sonorous?
and therefore, we hear drumbeats at a rate of four times per second, even if this frequency is not enough for our brain to combine the beats into a sound of a certain pitch.
In the meantime, it’s time to move with our drum straight to Scotland.
The scientists gathered an audience in the burial chamber and began to beat the drum at a speed of four beats per second (frequency of 4 hertz). The audience who listened later admitted that during the drumming they had unusual sensations - they felt that the sound in a certain way affects their pulse and breathing. Some said that if the drumbeat lasted longer, they would breathe more quickly. But during blows of the same force, but slower, from which the space did not resonate, there were fewer such complaints.
Burial chamber at Stony Littleton burial mound (England).
Of course, such sensations are subjective, but when NASA scientists when designing a rocket studied the effects of vibrations on the human body, they found that different parts of the adult's body resonate at different frequencies. Individual internal organs at certain frequencies vibrated more intensely, causing a significant "inhibition of the vital functions of the body and unpleasant sensations." And what is the resonant frequency of the human body? Yes, exactly what the researchers of the burial chamber came to in Camster Round - 4-5 hertz.
Maybe the people of the Neolithic era, hitting a drum and causing an infrasonic resonance, believed that they were communicating with spirits, deities or ancestors? Studies of the 1970s showed that at a frequency of 4-5 hertz, people feel dizzy and generally feel unwell (vibrations increase, responding in internal organs), but they also fall into drowsiness, they have a feeling as if they are swinging and now- they will fall.
Perhaps the architects of the Stone Age, when designing buildings, took into account their special resonant qualities? However, if the resonant sound seemed to them the sound of the other world, caused infrasonic vibrations in their own bodies and even changed their consciousness? Interestingly, and the disturbed neighbors did not appeal to their conscience?