The Research for an Archaeoacoustics Standard

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The right approach to this new complementary science for archaeology

 

Paolo Debertolis*, Slobodan Mizdrak**, Heikki Savolainen***

 

*Department of Medical Sciences - University of Trieste

  **DEMIURG, Institution for Energy and IT - Zagreb, Croatia

*** HSS Production, Audiovisual Impressions Helsinki, Finland

 

Scientific paper presented at Congress “The 2nd Virtual International Conference on Advanced Research in Scientific Areas” (ARSA-2013) Slovakia,  December 2 - 6, 2013.

Original paper for download here

 

Abstract — Research into archaeoacoustics and physical phenomena in ancient sites is still very much at the  developmental stage. Currently there is no practical standard to study this complementary discipline of archaeology. During the three years our group has been studying archaeoacoustics and natural phenomena, we have been able to explain some enigmas of ancient archaeological sites that were not possible to explain in other ways.

Following our experience, we spent time in our laboratories developing an archaeoacoustic protocol that can be applied to the investigatation of any archaeological site. Indeed it is important to define a standard at international level so that other researchers can use the same methodology to repeat previous findings.

Keywords: archaeoacoustics, infrasounds, low frequencies, ultrasound, SBRG standard, archaeology, SBSA

 

1 - Introduction

Archaeoacoustics is a new complementary discipline for archaeology that can explain why a particular ancient site was considered sacred, or why an ancient structure was built or carved in stone. We start from the concept that the ancient times were not silent and noiseless. Indeed, music and the vibrations produced by instruments were the highest kind of  culture in human civilization for along time. Through research it is possible to demonstrate that in the Neolithic and later periods the knowledge of acoustic phenomena was well known and used in the rituals of that period ^[2,3,4]. Research over three years by SBRG has shown ancient populations were able to influence their perception of the human body using sound to obtain different states of consciousness, without the use of drugs or other chemical substances. Further, ancient people were able to detect natural phenomena to create a similar state of altered consciousness ^[2,3,4].

Other researchers have found similar results in their research, but without a common protocol it has not been possible to compare different sites with similar characteristics  ^{[5,6,7,8,9,10]}.

As a result, SBRG group developed a new  standard that can be applied to the analysis of ancient sites in Europe and the rest of the world. We called it SB Research Group Standard for archaeoacoustics or SBSA for short.

 

2 - The archaeoacoustics research field

There are two main fields of archaeoacoustic research analysis; the first concerns the study of the resonance or reverberation phenomenon of ancient structures built for a particular purpose for example, rituals, music, or speaking performances. The second concerns looking at ancient sites with a natural phenomena that have a direct effect on the human body and brain in particular. 

In the first field, it is necessary to analyse sites using electronic sound generators at the beginning of the research.

After identifying the right frequency, other characteristics such as the best knots, the optimum position to achieve a resonance effect, or the best effect for a musical instrument or voice are considered. This is not a great problem as an electronic sound generator is easy to use as there are a lot of simple computer programs which can generate the required range. SBRG’s method uses a laptop with active speakers (portable battery or mains electricity operated). Testing of the acoustic properties of instruments is carried out using a shamanic drum (made from animal skin as opposed to synthetic material), the human voice is tested using harmonic songs which maintain the same note for a long time. SBRG uses both male and female singers for this purpose.

In the second field of study, the analysis must be more detailed and complex. Many ancient sites have been considered “sacred” for thousands of years, with a number of structures built on the same place throughout history. So the analysis should not be limited to the present structure, but also to it surroundings.

“Sacred sites” are those geographical locations that a particular social group deems worthy of respect and veneration; typically places of worship and/or used for other spiritual or religious purposes. As such, they can be desecrated or defiled, hence are protected in one way or another. The ancient Greeks used the term ‘topos’ to refer to the physical, observable features of a locale, and the word ‘chora’ to refer to those qualities of a location that could trigger the imagination evoking a mythical presence ^[7].

SBRG has tried several analysis methods to verify our results, after three years of  archaeoacoustic research conducted in the South of England, Italy, Bosnia-Herzegovina and Serbia we have produced a sophisticated and reliable standard which can be used by any researcher in archaeology to test a sacred location.

 

Fig. 1  - The study of the resonance effect using the SBRG protocol inside the ruins of the South-West tower in the imperial palace Felix Romuliana (III century a.C.)  in Gamzigrad, Serbia

 

3 - Ultrasounds, infrasounds and audible low frequencies

There are many scientific papers that state mechanical vibrations can have a positive or negative influence on our health, with several predominant sources of naturally occurring ultrasounds, very low frequency and infrasound found in the environment ^[3]. Depending on age and gender, humans can perceive sounds in the range of 20hz to 20Khz, in some cases sounds above 14-18Khz are not audible to the human ear. Careful measurements have shown that hearing does not abruptly stop at 20Hz, but the ear can register infrasound if the sound pressure is sufficient. Frequencies above 20Khz are considered ultrasound whilst frequencies below 20Hz are considered infrasound ^[14].

Low frequency sound has a relatively long wavelength and low material absorption rate, hence it has the ability to travel vast distances. These properties make it possible to achieve a profound effect on vast tracts of acoustic space with the production of high sound pressure level acoustic waves. Low frequency sound is non directional in it’s propagation and therefore has the effect of enveloping the individual without any discernable localized source.

Natural low vibrations with an absence of high pressure can have a positive influence on human health, some people perceive very low-frequency sounds as a sensation rather than a sound. Infrasounds may also cause feelings of awe or fear in humans, given they are not consciously perceived, it may make people feel that odd or supernatural events are taking place ^[15]. It is possible to hypothesize that where there are a lot of natural low vibrations present, ancient populations considered these sites to be “sacred”.

The same argument could be applied to natural ultrasounds. The upper frequency hearing limit in humans of approximately 20,000Hz is due to limitations of the middle ear, which acts as a low-pass filter. However, if ultrasound is fed directly into the human skull bypassing the middle ear to reach the cochlea then it is then possible to hear these frequencies through bone conduction ^[11]. Because in humans the upper limit pitch of hearing tends to decrease with age, children are able to hear some high frequency sounds that adults cannot ^[16].  Ultrasounds are well known and used in the medical field. Ultrasonography is a diagnostic medical imaging technique used to visualize many internal organs with real time tomographic images. Ultrasound is used for healing inflamed tissue and for therapeutic applications or in dentistry for cleaning tartar from teeth. Although the long term effects of exposure to ultrasound at strong intensity are still unknown, medicine currently considers the benefits to patients outweigh the risks. In contrast to medical applications, ultrasound has also been studied as a basis for sonic weapons, due to its direct effect on the human body and nervous system. Applications that have been developed include riot control through the disorientation of attackers with lethal levels of ultrasound used like a gun. In fact high frequencies can readily be absorbed by materials and being highly directional they have been incorporated into the design of acoustic weapons. It is probable that natural emissions of ultrasounds were heard by very young people of ancient civilizations as a supernatural sound, but in the rest of the population these were felt only as a good or bad sensation relative to the perceptible frequencies in a particular location along with the mystical aspect of the site.

 

4 - Materials and methods

Because archaeological sites can sometimes be influenced by electro-magnetic pollution, it is important to use sophisticated devices to avoid poor results. Likewise researchers have a chronic need for research funding, and should not have to spend too much on the necessary equipment. Use of gain control in recording devises is very delicate. In silent places, maximum gain for recording is used. In more noisy environments gain is determined with 0,775V/0dB AES/EBU standard.

The equipment used by our group consisted of dynamic high-end recorders extended in the ultrasound field with a maximum sampling rate of 192KHz (Tascam DR-680) or sampling rate of 96KHz (Tascam DR-100 and Zoom H4N equipment).

The microphones used have a wide dynamic range and a flat response at different frequencies (Sennheiser MKH 3020, frequency response of 10Hz - 50.000Hz) with shielded cables (Mogami Gold Edition XLR) and gold-plated connectors.

 

Fig. 2 - The extremely flat response of Sennheiser MKH 3020 microphones with a greater sensitivity both in low frequencies and infrasound than in the ultrasound field

 

Ultrasensitive omnidirectional microphones (Aquarian H2a-XLR Hydrophone, frequency response from 10Hz to 100,000Hz) are used to accurately obtain any possible resonance response from the water in the bottom of the chambers. This type of microphone has a wide bandwidth and is used by sea biologists to hear whale song several kilometers away. Sound is transmitted very quickly in water, with the body of water acting as a reflector capable of capturing the resonant vibrations ^[2,3].

For Ultrasounds we use a Pettersson D1000x ultrasound detector with a 500Hz-305kHz audio recording range. This is a light and easy to use device but the most expensive piece of equipment.

Pro Tools ver. 9.06 software for Mac is used to analyze the various recorded tracks, Praat program version 4.2.1 from the University of Toronto and Audacity open-source program version 2.0.2, both for Windows PC are also used.

Before recording a spectrum analyzer (Spectran NF-3010 from the German factory Aaronia AG)was used to search for electromagnetic phenomena that could be present in the surrounding environment leading to a potential negative influence on the results.

After three years of archaeoacoustic experience, in September 2013 the SBRG research team members gathered in Zagreb (Croatia) at the Demiurg D.O.O laboratories to develop an archaeoacoustic protocol designing a standard applicable to any archaeological site. Indeed it is important to define such a standard at international level so that other researchers can apply the same methodology to repeat previous detection. Most of the constructive criticism of our archaeoacoustic papers received over the last year, concerned a possibility that radio waves could have contaminated and tainted our results by infiltrating the ultra-sensitive microphones used. This is a possibility because condenser microphones are sensitive to radio waves, but only if these radio waves are very powerful and very close ^[2,3,4].Besides mobile phones (which are always strictly switched off, with the battery removed, because even when turned off mobiles phones regularly give the user's location through occasional pulses) the main concern was from radio waves originating from unusual terrestrial electromagnetic fields; either from the abnormal diffusion of the magnetic field or from tectonic movements of the Earth's crust. In order to rule out any possibility of the above, the physics researcher of the group, S. Mizdrak, designed simple electromagnetic sensors (coils) that could be used at the same time as microphones, these were plugged into the digital recorder normally used in archaeoacoustics (which has six to eight channels/three or four stereo tracks).

 

Fig. 3 - The eight-track digital interface (MOTU 896mk3 fw 800 digital interface) that was used to connect the various microphones and sensors to the computer. Ipad is used for fast musical key/frequency detection

 

The test used microphones for the air diffusion of sound (Sennheiser), underwater microphones (Hydrophones) and ultrasound detector (Pettersson D 1000X which directly transforms ultrasounds into audible sounds)  as well as two sensors (Demiurg) with different electromagnetic wave sensitivity.  These can detect if there are any magnetic fields nearby, whilst simultaneously recording sound vibrations, thereby giving more reliable results. The graph on the computer shows different waves recorded from each source.

 

Fig. 4 – This image shows the six tracks (three-track stereo) obtained from the digital recorder. The two graphs in the middle were obtained from electromagnetic sensors with different sensitivity, these highligh some of the noises picked up by one of the sensors, while the other tracks show the recorded sounds from the microphones (these monitoring operations were carried out in the laboratory in Zagreb)

 

A trained researcher can distinctively hear an anomalous vibration when the headphones are connected to the equipment. The graphic confirms the sound anomaly within a few minutes. 

In order to derive the basic guidelines for archaeoacoustics, the equipment was tested in the areas of Piljenice, Sisačko-Moslavačka (Croatia), located about 100 kilometers from Zagreb. This area is totally surrounded by the Croatian plain and it is completely free from anomalous electromagnetic phenomena, thus it was used to create a baseline with the absence of acoustic or electromagnetic anomalies.

Once the basic archaeoacoustic standard has been determined it is possible to check whether a particular archaeological site has any acoustic or electromagnetic phenomenon, either induced or natural, that can affect the psyche of a person. It is now possible to immediately identify a spurious phenomenon resulting from any human activity in the area that can affect the recordings made at a specific archaeological site. For this purpose and to have a comparison, recordings were also collected from an industrial environment of Zagreb where there are very high-levels of electromagnetic pollution.

One of the most important aspects of archaeoacoustics is to avoid any electromagnetic interference with the equipment. The above method has resolved this problem.

 

Fig. 5 –  A small lake in the Pilijenice area was used for baseline calculations with Aquarian Hydrophones submerged in water

 

 Fig. 6 – The high end Tascam DR-680 digital recorder

 

 Fig. 7 – The new sensors with different sensitivity (300Ω) built in Demiurg laboratories  (Zagreb) which transform electromagnetic impulses from the environment, into electrical impulses used by the digital recorder

 

 

Tab. 2 – Scheme for simultaneous recording analyze 6-tracks of 192kHz audio

 

The electromagnetic sensors built by Demiurg are very easy for anyone with practical knowledge of electronic devices to build. Without entering into too technical a description, they consist of two little condensers and one copper coil. The different diameter of the coil modifies the sensitivity of the device. The frequency response is linear from 5Hz to 99.5KHz to cover any frequency (VLF, Very Low Frequencies and LF, Low Frequencies radio waves) that could influence the microphones. It can also point out natural emissions present in an archaeological site.

 

5 - Discussions and results

The standard is based for using the same recording timeline for audio and electromagnetic waves. This makes possible to analyze precise moment simultaneously in every track.  Once the basic standard of archaeoacoustics has been determined it is possible to check whether a particular archaeological site has any acoustic or electromagnetic phenomenon, either induced or natural, that can affect our equipments. It is now equally possible to immediately identify a spurious phenomenon resulting from current human activity in the area, which could affect the recordings made in a specific archaeological site.

The SB Research Group Standard for archaeoacoustics (SBSA) has since been tested in archaeological sites in Europe.

 

Fig. 8 – Measuring in Felix Romuliana palace

 

For example, the electromagnetic (Demiurg) sensors were used at the imperial palace Felix Romuliana (Gamzingrad, Serbia) in November 2013. Here it was possible to identify a spurious source of electromagnetic impulses from a military base in the neighbourhood that appeared initially as an anomaly in our initial archaeoacoustic measurements. This showed up in the sound graphic as an anomalous wave (50-60kHz) we were subsequently able to eliminate a human made sound from the site. Searching nearby, we found the real source of this anomaly, a military beacon (see figure 8).

 

Fig.  9 – The military beacon at a base some kilometres from the Roman imperial palace of Felix Romuliana

 

To avoid any electromagnetic pollution that could invalidate the results, a quick computer analysis was carried out.

This method was used at all archaeological sites where it was possible to identify any noise interference. However, using this method it is not possible to eliminate the source of the interference, the process of clearing the recordings has to be done in the audio studio with this taken into consideration.

 

 

Fig. 10 – The electromagnetic sensor spectrogram. Above: silent natural situation, below: aspect of electromagnetic interference

 

6 - Conclusions

Microphones were also subject to numerous tests in the Zagreb laboratory to investigate their sensitivity to electromagnetic phenomena by means of a radio wave generator, which provided further evidence of the very low sensitivity to radio waves of the shielded cables and of all the equipment used for the tests. The latter should finally put the word “end” to all criticism raised some time ago over the inaccuracy of the method. Indeed the results strongly confirm all the data previously published by the research group ^[2,3,4].The newly-devised procedure (SBSA protocol) will be used in all future archaeoacoustic studies by SBRG and it constitutes a repeatable standard of reference for anyone doing research within the archaeoacoustic field. It is a simple, easy to use method not too expensive for any researcher who wants to test the archaeoacoustic characteristics of an ancient site. Archaeoacoustics is an interesting and easy method to use to understand a lot of information from an archaeological which is not possible to obtain in any other way.

 

Acknowledgement

SBRG are grateful to Department of Medical Sciences of the University of Trieste (Italy) for supporting this research and in particular to the Director, professor Roberto Di Lenarda.

Also our thanks to Pettersson Elektronik, Uppsala, Sweden.

A sincere thank you to our scientific assistant,  Nina Earl, for her support in the drawing up of this paper.

 

References

 

 

 

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