Starting the analysis of Alatri archaeological site from archeoacoustic point of view

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Tag: archaeoacoustics, Alatri, polygonal walls, low frequency, infrasounds

By the invitation of the independent researcher from Alatri, Ornello Tofani, SBRG research team through prof. agg. Paolo Debertolis began a study about archaeoacoustics on Alatri acropolis.

For now we only have used the sensitive microphone equipment to seize any sound vibrations both in the field of ultrasounds and infrasounds or low frequencies.

The tests were carried out over two days in mid-August 2013 in different points of the acropolis in the early hours of the morning to minimize the noise disturbance created by human activities.

This megalithic structure situated in the province of Frosinone (Italy), it has walls with pentagonal block perfectly joined without the use of mortar or other binding agent. Similar structures can be seen in the extraordinary Peruvian city of Cuzco, but Alatri has also been shown to possess unusual archaeoacoustic capacity.




  Fig. 1 - The stunning walls of polygonal blocks Alatri (Frosinone)


 Fig. 2 - The Stone of the Twelve Corners in Calle Hatun Rumiyuq in Cuzco (from Wikipedia)


  Fig. 3 - One of the huge stones of the temple located in the center of the acropolis and which now forms part of the basement of the cathedral dedicated to St. Paul and then to St. Sixtus I °. It does not seem to be much less than its equivalent in Cuzco because it has ten corners



 Fig. 4 - The “Porta Maggiore” of Alatri in the outside view (above) and inside (below). It is estimated that the lintel above the door has a weight of 27 tons


There is in fact a low frequency sound at a reduced volume at various points in the acropolis. This type of mechanical vibration, comes from the subsoil. It is possible that it has originated from tectonic movements of the underlying deep planes and may have a substantial direct effect of relaxation on the human organism according to the frequencies found capable of interfering with the brain activity  in the positive sense.

This last statement should be taken with caution and should be considered only as a preliminary result of this study. Therefore we will require further investigation, which will be held in December 2013 and also in subsequent steps, to assess whether the seasonal rhythm and the magnetic activity of the sun to be able to change the course of these sound characteristics present in the acropolis.


 Fig. 5 - The graphic analysis of one of the recorded files from Alatri. It is present a conspicuous component of low frequencies with a broad peak around 34Hz. Further analysis is needed to verify the behavior over time of this issue



 Fig. 6 - An image of procedures for listening and recording made in the acropolis


I mention that we have already found these frequencies by SBRG also on the hill of Visoćica (or Bosnian Pyramid of the Sun) in Bosnia and Herzegovina, which has a significant effect on who goes to the top of it. But at this point we can have the doubt that, as the most famous Machu Picchu in the Urubamba Valley in Peru, the original construction of the acropolis would have had a ritual reason and only later it was adapted for defense purposes.

Paolo Debertolis - August 26, 2013



This is the "Voice of Alatri." The recording was made at 6 am in order to minimize the noise of human activities. To listen you must use a high fidelity stereo headset with a large component of bass frequencies. Otherwise you can not feel anything. The sound is similar to a burner that will continue to operate under the city, there are also natural spurious noises due to the environment. The file is in mp3 format, click to listen here