Company Logo

SBRG logo

SBRG office



Warning to the readers

Archaeoacoustic analysis using new TRV camera (Variable Resonance Camera) technology

TAG: archaeo-acoustics, archaeoacoustics, hypogeum, Cividale del Friuli, resonance, ultrasound, shamanic drum, TRV technology, SBRG, SB Research Group

SBRG research group recently begun a collaboration with researcher Daniele Gullà and Florentina Richeldi, to undertake a deeper analysis of previous results obtained using the latest TRV technology (Variable Resonance Camera). This technology was used for the first time in the hypogeum of Cividale del Friuli, to evaluate the resonance effect of some of the chambers located on two different levels.

The resonance characteristics of this hypogeum was established over several sessions during the research that began in early 2013 and later published in the international scientific literature with two peer-reviewed papers (here and here). The results seem to confirm the ritual origin of the conformation of the Hypogeum and not just as a storage of funerary urns, a hypothesis proposed and currently supported by some historians. In contrast, our hypothesis is that the underground structure is connected to a Mother Goddess cult, given the strong influence on the local population of the rites originating from Balkan immigrants since Neolithic times, recognized by historians. This could potentially backdate the construction of this ancient temple considerably.

Wanting to build on the studies carried out, we decided to conduct further research by monitoring the state of consciousness of people during ritual singing or chanting of mantras tuned to the resonance frequency of the chambers.

In the coming months, monitoring via an EEG (electroencephalograph) portable device in collaboration with the service of Neurophysiology of the General Hospital of Trieste will be undertaken as an extension of research in this field, which has already been published in the international literature (here).

Before proceeding with this however, we wanted to explore the altered states of consciousness that can be achieved through the resonance phenomenon sought by the builders of the hypogeum. For this reason, a collaboration with researchers Daniel Gullà and Florentina Richeldi, who have a wide experience in the use of TRV technology, was begun to test the level of consciousness of some volunteers using this new method of analysis. The results from this technique will be particularly useful to compare with what the EEG equipment that will be used in the coming months.

The “technology TRV” (Resonance Variable Camera) needs a little explaining in order to understand how it was applied in this experiment and how it might be applied within the archaeoacoustic field.

As a premise, it is important to know that there is a direct correlation between emotional and functional states of the human body with the precise parameters of controlled motion reflection. Until recent times quantitative parameters and efficient information of the movement of the human body were not established. Bernstein and Mira Lopez (psychodiagnostic miokinetics) studied the micro-mobility of the human body and found that it represented a sophisticated mathematical problem. For example, it has been shown that the vertical balance of the human head is controlled by the vestibular system, and they described it as a reflex function. But the balance of the human head controlled by the vestibular system can also be considered as an extension of locomotor activity (micro-mobility of the head). The analysis of micro-mobility of the head and of other types of reflexes which control the motility of the human body are able to provide a lot of information on the state of consciousness of the examined subject. From the physical point of view, the mechanical oscillations of the head are a vibrational process, whose parameters provide a quantitative correlation between energy and mobility of the object. Information on the integral parameters of mobility of the head can be obtained by using video analysis TRV (Variable Resonance Imaging Camera) technology, which provides quantitative information of the periodic movements of any part of the imaged object.

In the image provided on the primary monitor which are represented by pseudo-colours, each point represents the parameters of mobility in the frequency of the examined subject. As in other biomedical imaging (ultrasound, NMR, IR, X -ray), the TRV is a method of image analysis that is based on data of micro-mobility models and introduces a new term, emotional vestibular reflex or “reflection of vestibular energy” (REV) which indicates that the coordination of the movement depends on the emotional and physiological state of mind and that is affected by these factors.

To date, the system has been primarily been used in the security and anti-terrorism field. People in an abnormal state of mind (agitated or stressed) show a different color in the video image creating around them a kind of aura that can facilitate their identification in the middle of a group of people, for example in the hall of an airport.

The same principle is already used in medicine for the early diagnosis of certain diseases which imperceptibly alter the general state of the patient. The human vestibular system receives information from almost all districts of the physiological organism, from the cardiovascular system to body temperature. This information is used to support the physiological homeostasis of the human body, and any significant signal given by some diseases or emotional stress disturbs this equilibrium.

The software program connected to the TRV technology allows analysis of stress or other levels of biological parameters, which are important for regular monitoring of mental/emotional balance.

The algorithm of the stress equation includes different filters, settings and adjustments which can be configured within the system software. In particular by exploiting the perception of the system of micro-movements of the left and right part of the body and how its correlates to vibrations in the examined subject. A high level of stress in the subject corresponds to particular states ofasymmetrical vibrations in the body which are clearly detectable by the system and signaled to the operator.


 Fig. 1 - The TRV system used in the experiment


The TRV image analyzer system is used to monitor vibrations in normal or altered states of consciousness, the so-called Human Energy Field (Human Energetic Field - HEF). In a little square on the PC screen the image of the subject is shown using a spectrum of false colours, with a graph corresponding to the initial position. Later the software shows, through the variation of colors in the image, a transition to an altered state of consciousness, sometimes reaching up to the total disappearance of the image itself or to a change of colour to a single color tone. The change from the initial multicoloured to a single color state indicates that the vibrations are passed by a wide spectrum of frequencies to a narrow spectrum, indicating a situation of coherence of the examined subject.

In conclusion, we can say that the detected spectrum of frequency changes completely when the examined subject enters into an altered state of consciousness. All the parameters are analyzed and stored from moment to moment by the cameras software. At the end of the trial a "report" can be generated showing the spectrum of vibrations, that shows the depth of meditative state and the fluctuations of the intensity of the vibrations of the body of the examined subject. In the pictures below there is a distribution of horizontal colored stripes around the vibrating objects (rows represent obtained individual frequencies). They horizontally represent the spectral distribution of vibrations in a band between 0.1 and 10 Hz according to a scale of pseudo colors from purple to red (shown below).


 Fig. 2 - Images converted to a scale of pseudo colours in relation to the frequency in Hz


The vibrations generated in various parts of the human body normally vary continuously both in amplitude and in frequency. On the PC screen a large panel shows the image of the person and around him appear horizontal lines of various colours and lengths that are the result of the method applied to the vibrations detected. The vibration frequency is shown by the color of the line, according to the colour scale shown in the image above. Another panel in the bottom left of the PCs screen, shows three graphs of the spectral characteristics.

In conclusion, this whole method is therefore aimed at studying the functional state of the human body directed towards the recognition of the emotional state. The algorithms for determining the emotional state are based on a system of mathematical statistics, principles of coordination of movement, and the logic of behavioral psychology and comparative tests.

Back to the results of the experiment carried out on April 13th 2014, which was carried out in  chamber D of the hypogeum, located on the third level down after the central hall located on the first level for comparison to the chamber D, marked with the letter A on the map.

 Fig. 3 – Map of the Hypogeum of Cividale del Friuli


Two singers, one male and one female positioned themselves within chamber D to provide coverage of the entire frequency range. However, as noted in our previous research only the male voice was able to solicit the structure using a mantra chanted with monotone tuned to the chambers resonant frequency around 103Hz.

The audio recording control was performed according to the SBRG Standard for archaeoacoustics (here). In this case the equipment consisted of a high dynamic range recorder, extended both in the field of ultrasound and infrasound with a sampling frequency rate of 192 kHz (Tascam DR-680).
Condenser microphones with phantom power with such a wide dynamic range and flat response at different frequencies (Sennheiser MKH 3020, frequency response of 10Hz to 50,000 Hz) with shielded cables (XLR Mogami Gold Edition) and gold plated connectors were also used.

The microphones were placed on the other side of the chamber in respect of the singers position and mounted on two tripods (see Figure 5).

Given the small size of the chamber D, the recording volume was adjusted to a value of- 9dB in order to avoid recording distortions.

The camera used in this TRV system has a common CCD backlit, with a three MegaPixel sensor. The protective anti-aliasing filter was removed to extend the vision beyond visible light into the infrared (IR) and ultraviolet (UV) range. It has a system of rotating LEDs from infrared to visible which generates ultraviolet light and synchronises with the rotation of the light at will from 1 Hz to 10 KHz . There is a connection to a PC, but there is also the capability to save videos to internal flash memory. The lens is a 25 mm quartz-fluorite with passband about from 200nm to 1800nm


 Fig. 4 - The camera used in the experiment


The camera apparatus was placed at the same side of the microphones on a tripod, while the system software has been loaded on a laptop PC positioned at the side of the chamber.




 Fig. 5 – In the image the examined subjects placed in the nodes of resonance (location to get the best effect of resonance in the chamber) and the operator of TRV system on your computer


 Fig. 6 – The frequency graph recorded during the experiment. There is a high peak around 101-103Hz caused by the voice that is reinforced by the resonance phenomenon. The other harmonics of the voice are at a significantly a lower level


 Fig. 7 – The TRV camera was positioned on a tripod located on the other side of the room to the singers. It is visible LED generating IR and UV in front of it


At the beginning of the experiment the TRV system, placed in front of the examined subjects, reported a baseline normal situation in front of the camera.




 Fig. 8 – The basic aspect at the beginning of the experiment before intoning the mantra. In the foreground the female singer (a little part of the front), with the male singer in the background


After a few seconds from the beginning of the experiment there is a background noise between 2Hz and 7 Hz after the triggering the vocal resonance, which saturates the measurement of the environment.



 Fig. 9 – The background noise (2-7 Hz) after the resonance phenomenon begins (few minutes) which saturates the environment of chamber D


Subsequently, the frequency is lowered (0.1 Hz and 4Hz) signaling the balance and homogeneity of the entire body of the subjects positioned in chamber D. This has led to a gradual disappearance of the figure at the bottom of the chamber, with the figure closest to the camera (more easily detectable) started to become opaque.





 Fig. 10 – In these images is evident the progressive inability of the system to distinguish the figure at the bottom of the chamber from its surrounding environment, that is vibrating to a synchronous manner to the subjects concerned



 Fig. 11 – The homogeneity of vibration between 0.1 Hz and 4 Hz , present throughout the environment of chamber D, after a few minutes of stress by the resonance phenomenon, the figure disappears completely from the bottom of the chamber. So only the red marks of the reflectors on the jacket of the same subject remain which are evident only for the refractive effect of the same and the movement of the subject


So the software reported the transition to an altered state of consciousness, first veering to one shade of color, at which point the whole room began to vibrate at the same frequency as the subjects in question, until the image totally disappeared. The change to the single color indicates that the vibrations are passed by a wide spectrum of frequencies to a narrower spectrum, indicating a situation of coherence of all and towards a contemporary altered state of consciousness of the examined subjects, but also accompanied by vibration of the chamber that is tuned to the same frequency of vibration of the subjects under consideration. Which represents an unexpected result.

This altered state of consciousness was achieved by simply repeating a mantra for about 8 minutes, as documented by the audio recording.

The test carried out in a similar way to the chamber on the first level did not reveal any step contrary to altered states of consciousness.

In conclusion, the power of the rituals performed in ancient times in the chambers of the Hypogeum of Cividale del Friuli utilizing its resonance phenomenon triggered by a male voice (as shown here) or by means of a percussion instrument (here), is still today able to change the states of consciousness of those present. The objective findings observed by the RTV instrumentation represent something alredy detached from subjective perception of the people considered and variously reported by the protagonists of our previous research.

Ultimately the instrumentation used confirms that a "mystical" state can be reached after a few minutes by those who are subjected to the resonance phenomenon inside the chambers of the hypogeum.

Paolo Debertolis, Daniele Gullà, Florentina Richeldi – 16 aprile 2014


A sincere thank you from the SBRG research group to the owner of Cividale del Friuli Hypogeum, Mr. Gaetano Bront, for his helpfulness and kindness in allowing us to enter even at night his ancient monument for our experiments. Heartfelt thanks also to Mr. Federico Morandini, who patiently gave us the keys of the hypogeum to conduct our research. .A sincere thank you to Nina Earl, our scientific assistant, for her support in the drawing up of this paper.




Archaeoacoustic analysis of Ggantija, Gozo

Tag: archaeoacoustics, archaeo-acoustics, low-frequency, infrasound, Malta, Gozo, Bronze Age, Neolithic stone circle, Xaghra, Ġgantija, brain activity, SBRG, SB Research Group

As part of the research carried out on some of Malta’s Neolithic temples, we performed some interesting research on the island of Gozo with very good results especially in Xaghra stone circle.

The Temple of Ggantija was devoid of underground vibrations, however like Tarxien temples on Malta, nearby Xaghra Stone Circle appears to be a real nerve center of vibrational energy from underground.

This energy is a mechanical vibratory stress that appears to have a broad peak, reaching between 25Hz and 34Hz. It is extremely powerful, more or less comparable to what was found in the temples of Tarxien, but with a slightly longer high frequency range and oscillating just a little bit. Its origin is to be found in the movement of friction between the African and Eurasian tectonic plates close to the archipelago of Malta.


Fig. 1 - The line of contact between Nubia and Eurasia plates


Fig. 2 - Velocities of GPS stations along the Nubia-Eurasia plate boundary (Serpelloni E et al. Geophys. J. Int. 2007;169:1180-1200)


In addition to Tarxien, we found something equally powerful in our research within the temple of Cybele at the archaeological site of Felix Romuliana, Serbia.

The broad peak at Xaghra Stone Circle seems to intrude in the field of infrasound and in the audible band comfortably up to 40Hz. At this frequency, this vibration is clearly perceptible to an attentive ear and for those who are more sensitive, via the vibrator sensors of body (Meissner mechano-receptors).

This explains why to this day some meditation groups visit this place to carry out techniques of mental concentration for religious, philosophical or spiritual purposes. Access to the site requires the permission from the Maltese authorities, Heritage Malta.

In previous research in other sacred archaeological sites by SBRG, these vibrations are perceived by many sensitive people as unspecified energy from the ground, with a clear effect on the human body and in particular brain activity.



Fig. 3 - The extraordinary peak of low frequencies constantly present in all the recordings made at Xaghra Stone Circle



The stone circle is located a short distance from the most famous Ggantija Temple. It was discovered for the first time at the beginning of 19th century, then rediscovered in the 1960’s and subsequently investigated in a joint collaboration between the University of Malta and the University of Cambridge between 1987 and 1994. Following this excavation, it was then covered again to preserve its characteristics.

It is believed that the first settlement dates back between 4,100 and 3,800 BC. Subsequently, as with the Tarxien temples in Malta, it was adapted to become a burial place from the same community who practiced its rites near temple of Ġgantija around the period 3,000-2,400 BC.

Even though the Maltese/English archaeologists found many parts of skeletons, this now partially collapsed underground structure, was probably at one time a sacred temple. The fact that the remains were incomplete and separate lends to the theory that they were not originally buried here, but moved to this place, probably adapted as a mausoleum for the ancestors.

Originally this archaeological structure had a huge stone entrance that led to the steps to reach the caves below where some altars were placed. The whole surface area was surrounded by megalithic stones arranged in a circle, as to demarcate the sacred area located below. In the underground area there was a central hall enclosed by the altar and divided internally by large stone slabs all around the now partially collapsed caves.


Fig. 4 - Graphical reconstruction of the stone circle of Xaghra. Circled in red the two positions in which the microphones were placed


Our archaeoacoustic measurements were carried out in two main locations: a deep well on the side of the walkway leading to a stone staircase that leads to the central hall of the hypogeum; in a collapsed cave that overlooks the main hall of the Hypogeum (A and B respectively on the above image). The ultra-sensitive microphones (Sennheiser MKH 3020) were dropped from the surface without going into the deep wells because this is expressly forbidden by the authorities. In this way the shielded and sufficiently long coupled cables were left suspended so that the microphones did not touch the ground. This was done in this way in order to avoid friction with the ground by the microphones which would have led to the generation of spurious noises affecting the recordings. The position of the microphones appeared sufficiently deep and sheltered from the wind. Also, during recording we carefully assessed if the sounds coming from the microphones were genuine and not from the result of human activity or the movement of the wind. We repeated several recordings over this time period with a long pause between the different files.



Fig. 5 - The handlings to place the microphones present into the well at the side of the walkway which leads to hypogeum (position A in Figure 4)


In both locations A and B where the microphones were placed (at about twenty meters from each other), the same low vibrational frequency as an engine in motion was detected. The sound is more likely to be attributable to the underlying tectonic movements as opposed to underground streams, given the scarcity of this natural element in the Archipelago of Malta. In the vicinity of the megalithic circle there was no factory or human activity capable of generating a noise of this frequency, that we were aware of.


Fig. 6 - One of the caves that overlooked the main room of the hypogeum


 Fig. 7 - The archaeological site is protected by a fence and closed by a gate. Access is only possible on request to the government institution Heritage Malta. It is not possible the access the zone in the Hypogeum


As with other research carried out by SB Research Group at other archaeological sites in Europe, we can theorize that inside the stone circle was a “covered” hypogeum. Such a structure could certainly have acted to intensify the vibrations, in a similar way to how a sound box of a musical instrument works.

Such vibrations have a definite effect on the emotional sphere of those who stood in prayer or meditation in this hypogeum creating the real “sacred space” of the area of the most famous temple of Ggantija.


 Fig. 8 - During the initial listening before recording, it is important to assess by clap if the microphones may be affected by noise from the environment. In this case, it was verified that the microphones had been pushed so deeply as to be scarcely affected by the noise environment


 Fig. 9 - Even in position B (Figure 4) the sounds detected were similar to those detected in the well at the side of the walkway (A position)


We conducted thorough research of the sounds coming from underground in in the temple of Ggantija, but apart from the noise pollution from the sites nearby access road (at higher frequencies than those found in Xaghra megalithic circle) we did not find anything which compared to the sound spectrum found inside the stone circle.


Fig. 10 - Ggantija as seen in its entirety. Above: view from the hill in front of the temple. Below: the appearance of the temple seen from the back


The research also aimed to establish if there was any resonance phenomena inside the apses by playing musical instruments, however the presence of metal cages designed to shore up the huge stones of the site meant this was not possiblbe. They acted as interference obstacle in reflection of the sound waves, so we cannot pronounce definitively on this aspect of the temple.



 Fig. 11 - The presence of numerous tubes containing the stones frustrated any attempt to verify the presence of a resonance phenomena that could be stimulated by musical instruments (eg drums or percussion bells)


Equally the areas without props have undergone such alterations over the millennia, such as to alter their original form with domed roof  to make virtually impossible an adequate assessment in the field of sound resonance maybe desired by their builders.


 Fig. 12 - Even in the most sacred part of the temple the alterations or deterioration of the structures have meant that nothing has been detected


Fig. 13 - Plot of recordings made in Ggantija Temple, unlike in Xaghra stone circle, nothing unusual was detected. The peaks in the middle of the curve are simple ambient noise


It should be noted that some megaliths have similar holes to those at the Tarxien Temples. This could indicate that at the time they may have acted as transducer of vibrations coming from underground. Functioning in a similar way to bagpipe reeds, used to expand the vibrations coming from underground. However these vibrations are present in Xaghra Stone Circle, but not in Ggantija Temple.


Fig. 14 - The holes in the Ggantija megaliths, quite similar to those found in the Temples of Terxien


We wanted to find a base line noise in this area that could serve as a reference for the recordings in the above mentioned temples. For this purpose we chose the hill in front of Ggantija, where there are still prehistoric settlements. In particular, we dropped microphones through the entrance of a prehistoric tank (that is dry now), on top of the hill and dug into the rock.

The track recorded in the prehistoric tank is devoid of any peak from noises coming from underground confirming the uniqueness the Xaghra Stone Circle recordings.


 Fig. 15 - The hill facing the temple of Ggantija. The site of a prehistoric settlement which has not yet been deeply research


Fig. 16 - The dry tank excavated in the rock where our microphones were placed


Fig. 17 - Above: the look and feel of the recordings made in the tank. There is absolutely nothing significant. Below: the sound curve measured inside Xaghra Stone Circle for comparison. It is evident in this recording (as inside the stone circle) that there is a powerful vibration with a top peak of 28Hz


How did the ancient megalithic civilization become aware of the vibrations present in this area and the caves at Xaghra stone circle? We propose a simple answer, given the high noise level of those frequencies present in the human hearing spectrum they would have been heard by placing an ear to the ground for the transmission of vibration via bone conduction.

It is likely that these vibrations, close to the rhythm of brain wave frequency, created a sense of exaltation and mysticism in those present. When it was intact, it must have acted as a sound box for someone engaged in prayer or meditation. Probably he felt himself enveloped in the sounds of the womb of the Mother Goddess, and in touch with the depths of the planet.


Fig. 18 - Graphical reconstruction of the Xaghra stone circle inside Ggantija museum (Heritage Malta - Ggantija Museum)


Fig. 19 - Some of the votive objects found during the excavations of Xaghra stone circle (Heritage Malta – Ggantija Museum)


Our warmest thanks go to the Maltese institution Heritage Malta for giving us access to Ġgantija Temple for our research, and in particular, our gratitude goes to Dr. Daphne Caruna, curator of the archaeological site, who controlled, assisted and helped us during our surveys.

Paolo Debertolis, Nina Earl - April 5th, 2014




Preliminary archaeoacoustic analysis at Tarxien Neolithic Temples, Malta

Tags: archaeoacoustics , archaeo-acoustics, low-frequency, infrasound, transducers, Malta, Tarxien, Neolithic, SBRG, SB Research Group

A few days before and in conjunction with the Archaeoacoustic Conference  "The Archaeology of Sound" in Malta on 19th -22nd February 2014, a small group of SBRG members performed several archaeoacoustic measurements on some ancient temples in Malta.

In particular measurements were taken at the temples of Tarxien on the island of Malta, and the temple of Ggantija and Xaghra circle on the island of Gozo.

Thanks to Heritage Malta we obtained the authorization for admittance to places normally closed to the public to take acoustic measurements.

The Neolithic temples of Tarxien are in the town of Tarxien on the north side of the island. This is totally surrounded by houses and as a result, it was not very easy to take high-level recordings inside. The analysis of the recordings took a few weeks, but it looks like there is a very low frequency coming from underground in the range between 21Hz and 23Hz, encroaching sometimes infrasound frequencies with a peak of around 18Hz.


 Fig. 1 - Three examples of recordings taken in two different locations within the archaeological complex: the audio track is constant for each recording. There is a  large peak with a maximum of around 21 - 23Hz in almost all surveys, sometimes extending to 18Hz. The hump at the end of the plot in the range of the ultrasounds is an artifact determined by the characteristics of ultra-sensitive microphones, but no ultrasounds were detected inside the temples of Tarxien



Fig. 2 - The trace recorded in the nearby hypogeum of Hal Saflieni, located a short from the temples of Taxien. The very low volume at the start of the line of sound should not deceive: the recording was made at a lower volume. But whatever the volume of the recording, this does not change the result because the peak at 21 - 23Hz, detected in the Temples of Tarxiem, is missing. It is clear that these inaudible seismic noises are probably originating from a nearby geological fault (Malta is in an area with a lot of tectonic plate movements)

As we know and we have verified in previous research on ancient sites in Europe (Bosnia-Herzegovina, Serbia, South England, and also Alatri in Italy), this type of frequency, if at an appropriate volume and not too high, can have a positive effect on brain activity. This effect is particularly evident in people who practice meditation. During the measurements we also attempted to verify the presence of a resonance phenomenon within the comples’s two temples, those in the best condition for this purpose. Various musical instruments were used, from primitive shamanic drum to percussion bells, but without success. Unfortunately, the structure is too destroyed in its higher portions that are deemed to have been covered by a dome roof.


Fig. 3 - The operations of recording inside the temples


These temples were brought to light by the Maltese archaeologist T.Zammit in 1915 after some local farmers had complained in 1913 that when plowing the field above the temples, the plough was ruined by large stone blocks. These temples were further excavated in 1954 by English archaeologist J.D. Evans and four years later by D.Trump who discovered the re-use of them in the times of the Roman Empire as a cellar.

This Neolithic complex was initially built between 3,600 and 3,000 BC as a sacred place, but at the beginning of the Bronze Age (2400-1500 BC) the original temples were reused as storage of funeral urns. This indicates that the original population was replaced by newcomers with different social customs.


Fig. 4 - A look taken from the gates of the temple. At the center of the curator of the archaeological site that has helped us for a better understanding this structure



Fig. 5 - A few more striking image of the prehistoric complex that, as we see, is surrounded by a densely populated town


In addition in the 1950s, where a piece of the megalith was missing, the structure was reconstructed in several places using Portland cement. This ran the risk of restoring something not true to the original, but according to the tastes of the restorer. The type of material used, compared to the original coral limestone megaliths in their uncorrected position, may have been detrimental to the proper sound functioning of the old structure. Also the concrete reconstructions may have damaged the original stone. Unfortunately at the time of the restoration this problem was unknown.

The reconstructed parts of the megaliths appear very light compared to the original under infrared photography, whereas in normal photography, the remanufactured parts appear more visible because they are brighter. The infrared photography also cancels the dark color due to molds and lichens present on the surface of the megaliths and prevent you from grasping the structural element in its entirety.



Fig. 6 - Some infrared photographs which highlight the original stone (in gray) from the reconstructed concrete (in white). In infrared photography the difference between the two different materials is exaggerated by the reflection of sunlight



Fig. 7 - The same architectural element taken using two different techniques. Above: photograph taken with an Olympus E- 5 digital camera with proprietary software which enhances contrast. Below: the same subject taken with a modified Canon infrared camera. There is a clear lack of ability to reflect the sun's rays on cement that looks almost white in color, while the sky is almost completely black


The temple complex consists of four sacred temples. The first of which is located on the eastern side and built between 3,600 to 3,200 BC. Unfortunately despite the five apses being clearly visible, only the foundations remain. The South Temple is the most highly decorated with megalithic constructions that also contain the lower part of a colossal statue of a female figure and the East Temple with its walls of stone slabs and well shaped 'oracle' holes were both built between 3,150 and 2,500 BC. The Central Temple has six apses arranged on one floor and contains evidence of a cover arcs.

Our research group performed measurements on two of the four temples.


 Fig. 8 - What remains of the colossal statue of a woman (Mother Goddess) in the South Temple. This is a copy, the original is in the museum of Archeology, Valetta


With the vibrations from the subsoil, it was observed that some megaliths appear to act as vibration transducers and some concavities or holes in their inner seem to project and focus these vibrations. The mechanism appears to be very interesting and detectable by instruments: an ancient lost technology that can now be rediscovered through the use of today's sophisticated equipment, but once found only by the sensitivity of a person.

The holes found in the megaliths are very deep and are considered to have been used to support the foundations of some sort of barrier or door. But the direction of the holes seems rather directed to a greater sound diffusion of mechanical vibrations as a kind of forerunner to speakers. The mechanism discovered by our associate anthropologist researcher dr. Alesandro Severi, seems to provide an intriguing interpretation of  this archaeological site but requires further in-depth analysis. Certainly we to exercise caution before saying as reported above, so we are already preparing a new inspection on the site to recheck the measurements.


Fig. 9 - A sensitive hand can discern the low-frequency vibration of the air


 Fig. 10 - Graphical extrapolation of the sound from the megaliths


A sincere thank you to the curator of the archaeological site, Joanne Mallia, Prehistoric Sites Department of Heritage Malta, for her kindness and courtesy. Her help enabled us to have access to more parts of the ancient temple.

It will be necessary in the coming months to further survey the archaeological site to study what we found on this occasion.

Paolo Debertolis, Nina Earl - March 26, 2014




Our colleague professor Lucia Krasovec Lucas leaves our research group


It is with regret our colleague from Politechnic of Milano and founder member of SBRG, Prof. Arch. Lucia Krasovec Lucas, is reluctantly forced to withdraw her commitment from our research group. 

Of recent months, Lucia‘s academic obligations at the Politechnic of Milan have increased. So ends three last years of working together, during which Lucia always provided us with determination and professionalism. An example of this is the mapping of the Ravne hypogeum during our research in Bosnia-Herzegovina in 2011. As a consequence, the status and purpose of SBRG will undergo some changes.

She deserves our appreciation and gratitude as well as our good wishes for the new challenges that lie in front of her.

SBRG – February 11, 2014




Archaeoacoustical analysis of Cividale del Friuli Hypogeum using a shamanic drum

TAG: archaeo-acoustics, archaeoacoustics , hypogeum , Cividale del Friuli, resonance, ultrasound, infrasound, shamanic drum, SBRG, SB Research Group

On 21th of February 2014 we revisited Cividale del Friuli Hypogeum (Italy) to stimulate the resonance phenomenon in those chambers whose structure has been unaltered.

In particular, we wanted to test the resonance of one of the Hypogeum deeper chambers in which the effect appears to be more intense (chamber D on the map), this chamber is oriented within a few degrees of south.

Fig. 1 – Above: the map of the Hypogeum of Cividale del Friuli. Below: the entrance to the deeper chamber (marked D on the map)


This room is tuned to a frequency of around 101- 103Hz (102Hz on average), it is sensitive to songs and prayers (mantras) sung at this frequency by a male voice. The female voice, which does not have this range, is unable to stress the structure.

SB research group began to study this underground structure not based on the commonly held hypothesis that the Celts used it as a burial place, or it was used as a prison by the ancient Romans and Longobards. Our study was based on the hypothesis suggested by the independent researcher V. Maestra who suggested it is much older. He considered this structure to be a temple dedicated to the Mother Goddess. In fact this temple has sound resonance characteristics that would suggest it was geared for sacred rituals and not as a burial place.

During our study we found only two chambers (C and D of the map) to be sensitive to the resonance phenomenon. These are most likely the only rooms which have retained the original features and have not been modified in later times for a different use.

Our earlier research has been published in the international literature in the United States (here).

If we consider the Hypogeum of  Cividale to be a temple of Mother Earth whose date has been lost in time, we must consider that this cult was usually conducted by priestesses. For this reason we have compared it to the more well-known underground Hypogeum of Hal Saflieni in Malta notoriously dedicated to Mother Goddess.

But if priestesses conducted the religious rites in this structure, it seems counterintuitive that the only way to stimulate the resonance effect, which creates a strong emotion in those present in the rituals, was only through a male voice. Surely if our hypothesis is correct, there must be other ways to activate this process.

After taking this into consideration, we decided to use an easy to play acoustic instrument which would have been available in the historical period corresponding to the construction of a temple dedicated to the Mother Goddess.

We discarded wind instruments as the tone was too high or other methods such as glass goblets. Instead we looked at the kind of percussion instrument that is known as a "shamanic drum" still commonly used today in Celtic music performed in Northern Europe and also shamanic rituals.

This ancient instrument is found in virtually all cultures of the world and are still made today. It is a drum with one head, built on a circle in solid wood on which is stretched an animal skin, typically goat or deer, but skins can also be derived from different animals, depending on the area and culture.

These skins are stretched on the wooden circle still wet with ropes to reach the right amount of tension when drying.

Typically they range in diameter from 30 to 50 cm, and usually on the back side the shamanic drum is a handle. This can be made from ropes or parts of skins cut into strips and then tied, or with a wooden cross that allows it to be grabbed firmly with one hand while the other hand remains free to strike him with a wooden beater that can be made
of leather or other materials.

There are still a large number of craftsmen who can make such drums in many versions, and different patterns present on the skin can make a drum have a unique sound.

The sound is deep, but if the skin is damp from moisture, the tone changes as it vibrates less. The skin needs to be dry to produce the correct sound.

So the sound can change very quickly and is conditioned by the environment, if this is humid then the skin needs to be heated over a fire in order to obtain a more pure sound.

For our research we used a shamanic drum with a diameter of 50 cm made from goat skin. On the skin is a symbol of the Thunder Bird with two heads from Native American mythology, created by the craftsman who produced it. This design does not change the sound characteristics of the instrument, but it is purely for decoration.


Fig. 2 – The shamanic drum used during the experiment seen from the front


This drum has an average resonance frequency of around 55Hz when beaten at the center. As previously mentioned, the sound characteristics of this instrument can be undermined after a prolonged stay in the moist environment such as that found in Cividale Hypogeum.   This meant that at the start of the experiment the drums were working more efficiently than after prolonged exposure to the moist environment. The tone of the sound can also change depending upon where the beater strikes the skin, for example at the periphery the tone rises, but there is also a decrease in sound pressure that can be exerted.

The drum used in our experiment was placed at the end of the chamber D. As expected, the greatest effect was achieved by placing the drum in the sound node previously found. The term "node" refers to the point in the interior space of the chamber where the greatest effect acoustic resonance effect is felt. In this case about half meter from the bottom of the chamber and one meter in height. The resonance effect decreased dramatically the further away we moved from this point.


Fig. 3 – The drum has been used in different parts of chamber D, but the best configuration occurred in node sound (image below)



The frequency response of the structure was amazing, even though the drum had a frequency extension of i around 55Hz, the room responded at 103Hz, the frequency for which it is tuned. It is conceivable that the high sound pressure exerted by the drum or one of its harmonic vibrations put the chamber into this resonant vibration.

This effect amazed us, however graphical analysis of the recorded files has shown there are two very distinct peaks, the first from the shamanic drum, the second from the chamber.

If we look at the logarithmic plot of the recordings made during our  sound tests, we notice the presence of two peaks of greater intensity. If we put the cursor on the second peak in the graphic program, we can verify that the response of the chamber is tuned on 103Hz. This graphic
behaviour is the same one that is obtained by the male voice tuned to the same frequency of the chamber. If you point the cursor to the first peak it reads 55Hz, which is the average frequency of emission of the shamanic drum. As you can see, the sound response of the chamber in volume is equal to the sound pressure exerted by the drum. There are also higher harmonics of a smaller volume.


 Fig. 4 – The logarithmic graph that come out from the analysis of the recordings : two peaks of the same volume are evident, one determined by the sound of the drum (first from left ) and one from the chamber


By drumming at a certain rate, the chamber almost continuously vibrates. These vibrations, that are composed of frequencies in which we are investigating in another area of research using EEG, are capable of interfering with brain activity, and can create a state of ecstasy.

What seems clear at this point is that if this was originally an underground temple of Mother Earth, it was not necessary that a man was present to use his voice to generate the resonance response, rather it was sufficient that the Mother Earth priestess used a drum during a ceremony, beating at the right pace and in the right position (acoustic node). While it is conceivable that the onlookers were sitting on the seats carved into the rock in several places close to the celebrant.  We have verified that sound easily travels within the Hypogeum.


Fig. 5 – The digital recording equipment (Tascam DR -680) and Sennheiser mics (MHK3020), as from our standard SBSA protocol


On one of the recorded files after the beat of the drum it is possible to hear distinctly the response of the chamber that creates saturation within the microphones (here). To listen to this file you need to use a good pair of stereo headphones with a large bass component. If you use standard computer speakers you may run the risk of not hearing anything.


We had heard about the risk of remaining too long in the hypogeum due to Radon gas emissions from below, we wanted to measure the radioactivity using a Geiger counter (GAMMA - SCOUT model w/ALERT).

The environment was free from any radioactivity, we measured a maximum of 0.08 to 0.09 mSv/h. There is therefore no danger in this environment. It should be remembered that in the underground Ravne tunels in Bosnia, we measured a maximum radioactivity of 0.20 mSv/h. We have to recall too that the alarm threshold is set at 0.4 mSv/h, while values
greater than 0.60 mSv/h reveal the presence of a radioactive source.



Fig. 6 – The Geiger counter demonstrates a very low radioactivity levels because the underground structure is protected from the action of cosmic rays  and there is no presence of Radon gas


All recordings were performed according to the Standard SBSA protocol.

Paolo Debertolis - January 24, 2014


A sincere thank you from the SBRG research group to the owner of Cividale del Friuli Hypogeum, Mr. Gaetano Bront for his helpfulness and kindness in allowing us to enter even at night his ancient monument for our experiments. Heartfelt thanks also to Mr. Federico Morandini, who patiently gave us the keys of the hypogeum to conduct our research at all hours of the day and night. Thanks also to our new collaborator, Mrs. Dolores Dreosti, for her support in Cividale del Friuli researches.



Translated by Nina Earl


Login Form


Powered by Joomla!®. Designed by: joomla 1.7 templates hosting Valid XHTML and CSS.

Copyright © 2024 SB Research Group. All Rights Reserved.
Joomla! is Free Software released under the GNU General Public License.