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The Use of Infrasound: Exploring its Potential as a Non-Lethal Weapon

  • Writer: Anshuman Arya
    Anshuman Arya
  • Feb 13, 2024
  • 1 min read

 Infrasound: An evaluation of its potential application as a non-lethal weapon

By Anshuman Arya

Word Count: 3800

Submitted to SAE Institute, Oxford

In fulfillment of the Written Assignment

17th August 2012





Abstract

The concept of Infrasound and weapons development often being stated in the same breath is not a new one, although, not much is known to the general public due to a lack of published content and the issue involved being of critical importance to national security and disarmament treaties.


This essay intends to shed light on what information is already available about Infrasound and how we can form a roadmap, based on factual evidence, as to its future implications in our lives.


The opening introductory chapter places a strong emphasis on the technological progress of a nation being largely a result of its military prowess as has been seen from the dawn of civilization. It elucidates some examples and historical evidence of sound being used as a weapon and some of the common myths regarding Infrasound.


Then, the essay goes through some of the relevant physics behind Infrasound and its properties, natural and artificial sources, and some of the present day applications of Infrasound.


The third chapter, largely based around published surveys and studies, goes on to explain the reported psychological and physiological effects of Infrasound, specifically on the human condition, and on the way, de-bunking the sensationalized ideology of Infrasound being a “sonic killer”.


Finally, an overview of possible systems and the mythical weapon systems allegedly said to have already been developed, is presented, leading to the conclusion that Infrasound may not be a feasible assault weapon system at our present stand point.

Introduction

“I will ignore all ideas for new works and engines of war, the invention of which has reached its limits and for whose improvement I see no further hope” -Julius Frontinus, Chief military engineer to the Emperor Vespasian, c. AD 70

Since the time this statement was made, mankind’s technological progress has been exponential. To put things in perspective, we have progressed from primitive arrows to nuclear warheads, from the trireme to the ocean liner, from the balloon to space shuttles, from the chariot to the bullet train and witnessing the way we have been swept along by the tide of worldwide human events at the beginning of the 21st century, humankind is on the verge of a massive technological, sociological and cultural shift that may forever change the way we live. Julius Frontinus was of course mistaken to believe what he did, as further scientific and technological progress is inevitable.


To quote American historian William H. McNeill, “Anyone looking at the equipment installed in a modern house will readily recognize how much we in the late 20th century are indebted to the industrial changes pioneered in near-panic circumstances when more and more shells, gun-powder, and machine guns suddenly became the price of survival as a sovereign state.” (McNeill, 1984, p.331)

One has to look no further than their computer screens to see the truth in this statement. Defense Advanced Research Projects Agency (DARPA) in the United States of America was established at the height of the Cold War and their most famous contribution to the world is the Internet, designed specifically for the Pentagon as a communication network that could survive a nuclear war. (White, 2005, p.3)


The advancement of technology has relied on the competence of the armed forces of a nation (and government funding thus provided) since the time of Archimedes (built a revolutionary catapult for the army), through Da Vinci (designed siege engines, mortars, transport devices) to Oppenheimer (father of the atomic bomb).


This is not to say that the 2 impetus from the military-industrial complex is the only way humanity has propelled forward to technological advantage but it has, without a doubt, played a major role. The war/peace scenario has drastically changed in the chaos ensuing all over the world in the past 50 years with insurgency and terrorism at an all time high.


When faced with a threat of violence, a nation could do one of two things - withdraw from peacekeeping and humanitarian aid duties, or fight back; which is vicious circle as it inexorably leads to the loss of more human lives. But today, there may be a third option and most militarily advanced nations are looking seriously into non-lethal weapon systems.


Although related research is being conducted in the scopes of bioengineering, electromagnetism, low-kinetic energy weapons, restraining technology (Cerasini, 2002, pg.175-186) etc., for the purposes of this text, we will look closely at the prospect of sound as a non-lethal weapon, and more specifically, infrasound.


Perhaps the first documented application of acoustics in warfare goes back to the time of the Old Testament, in which it is stated that a single blast from Joshua’s horns caused the walls of the besieged city of Jericho to collapse. (Cerasini, 2002, pg.180)


More recently, in 1990, persistent blasts of blaring heavy metal music were used to drive out and apprehend Manuel Noriega out of the Papal Nuncio (a church) in Panama City where the fugitive dictator had taken refuge. (Rock n Roll assault on Noriega, 1996 [online]),


As we’ve seen various deployments of in the last couple of years, the most recent being the London 2012 Olympics (Thomas, BBC [online]), the LRAD (Long Range Acoustic Device) Corporation has developed a system, which emits a 2.5 kHz tone in a 30-degree conical field at the target and can be mounted on vehicles to act as a mobile unit in urban environments.


Ironically, according to the website, LRAD was first developed to support the protection and exclusion zones around U.S. Navy warships and today is advertised as a long range hailing, directed acoustic device. (LRAD website [online]) The reason why Infrasound strikes as an important force is due to the sensational journalistic articles based on the knowledge of allegedly what was a secret French weapons development program under Dr. Vladimir Gavreau in the late 1950s.


In one of such articles by Gerry Vassilatos (Vassilatos, 1996), Gavreau, and his team complained of periodic bouts of disconcerting nausea while working in the research facility and after a thorough search, no explanation could be provided as to the cause of the malady, but symptoms ceased when certain windows in the facility were 3 blocked.


It was later discovered that the source was a loosely mounted, low speed motor in the buildings ventilation system that was causing “nauseating vibrations”. Gavreau and his team turned their focus to this vibration, and after a lot of effort, came to the conclusion that it was a frequency they could not hear (measured to be 7 Hz) produced by the vibrations that was resonating in the vents and the building was acting as an amplifier.


Their hypothesis was strengthened when they blocked those windows, as this changed the tonal resonant profile of the enclosure and thus shifting the infrasonic pitch and intensity. Gavreau and his team conducted further research into Infrasound, but none of the empirical evidence or results of research were ever published.


Based on unfounded and unreliable information, the effects of Infrasound were highly exaggerated in many sensational articles in the 70s.


A selection of some press headlines (Leventhall, 2003, p.4) from the early years is:


• The Silent Sound Menaces Drivers - Daily Mirror, 19th October 1969
• Does Infrasound Make Drivers Drunk - New Scientist, 16th March 1972
• Brain Tumors 'caused by noise' - The Times, 29th September 1973
• Crowd Control by Light and Sound – The Guardian, 3rd October 1973
• Danger in Unheard Car Sounds - The Observer, 21st April 1974
• The Silent Killer All Around Us - Evening News, 25th May 1974
• Noise is the Invisible Danger - Care on the Road (ROSPA) August 1974

These articles in no way provide any purposeful information but rather point us to directions where independent analysis is required. As a result, reliable research material on the effects of Infrasound has been made available to the public based on official studies and surveys carried out by qualified researchers and organizations so as to propagate genuine information based on factual and theoretical evidence.


This essay aims to do the same.



Understanding Infrasound

Our understanding of Infrasound is still in its infancy because only very recently have we begun to see its capacity in interdisciplinary sciences. Much of the data procured about infrasound affecting the human condition or even coming close to being a cause of concern, comes from social surveys conducted to look into general noise complaints.


This has steered the scientific community towards analytical research into 4 the effects of Infrasound on the human body so as to come up with empirical data to infer conclusions from. These studies and surveys are what form the basis of this chapter so that our understanding of military-operational and humanitarian assessments need not rely on incomplete or even obscure sources.


Technically, Infrasound is any sound below the lower limit of audible sound viz. 20Hz. This is not to say that Infrasound is inaudible, as at loud enough levels, even a 1 Hz signal can be heard. It has been noted that we can discern pitch as low as 16 Hz but below that sound loses tonality and it becomes more of a bodily perception as compared to an audible one (Leventhall, 2003, p.7).


This has been a known fact for quite some time now as Infrasound is present in nature as a reckoning force that we feel during natural calamities like earthquakes, tornadoes, landslides, avalanches etc. where Infrasound gets amplified.


Infrasound is present in nature in calmer situations as well, registering as low as 10-3 Hz and might be associated with varied seismic and atmospheric phenomena such as thunderstorms and auroras, gusts of winds interacting with land and water bodies, solar flares penetrating from the atmosphere and even during meteor showers (Cody, 1997).


Infrasound is produced by man-made sources as a by-product of their operation viz. common installations in urban environments such as power stations, transformers, subways, and tunnels etc. as table 1 lists. As figure 1 suggests (Health Protection Agency Report, 2010), the changes in sound pressure levels produced by these sources are so low that we do not register them.


The standard for measuring sound pressure level, and our perception of it, is the decibel scale (dB), and metering systems, which have different weighting algorithms such as the dB(A), dB(C) and dB(B), are commonly used to meter and get a numerical value for audible range.1 For the purposes of Infrasound, a weighting curve called dB(G) is applied, which falls off rapidly above 20Hz, while below 20Hz it follows assumed hearing contours with a slope of 12dB per octave down to 2Hz, as illustrated by figure 2. (Leventhall, 2003)

Today, Infrasound is used in geology, meteorology and noise assessment. These applications apply various innovations such as the use of redesigned condenser microphones that work in conjunction with sound level meters operable in the range of 1-100 Hz based on the G- weighting; optical fibre infrasound sensors which consist of two optical fibres which calibrate to sound pressure based on the input from a compliant tube which has a pair of optical fibres wrapped around it that detect atmospheric pressure changes in the sealed tube (Leventhall, 2003); micro barometers and infrasound array detectors to monitor seismic and geological activity.


In the 1970s, the National Oceanic and Atmospheric Administration began a study of atmospheric infrasound to determine whether it could be used to improve warning capabilities for severe weather events such as tornadoes. It was found that many thunderstorms radiated infrasound, which could be detected by observatories more than thousand miles away. (Gupfinger et al, 2009)


Infrasound is one of the technologies being used by the proponents of the Nuclear Test Ban Treaty to monitor any nuclear activity, with over 300 facilities across the globe. Such application of Infrasound is highly promising and encouraging as it inevitably leads to further research into the field and more specifically into the consequence it has on human systems.



A summary of published health effects of Infrasound

A survey carried out in Denmark (Møller & Lydolf, 2002), in response to complaints where subjects reported their annoyance at low, rumbling sounds that robbed them off their sleep along with headaches and palpitations as side effects, led to inconclusive inference of the effects of


Infrasound as the levels were not exceeding stipulated environmental limits. These limits were set by the Environmental Protection Agency in 1997, which recommends that the indoor noise in dwellings should not exceed 85 dB(G) for infrasound and 20 dB(A) for low frequency noise (10-160 Hz). Of all the 198 respondents that reported a sensory perception of the sound, it was suggested that it might be a more subjective concern at hand and needed further exploration.


Many such surveys have been conducted based on similar complaints to authorities all over the world and have been duly reported in the findings of Persson and Rylander (1988) in Sweden, Tempest (1989) in UK, (Yamada et al., 1987) in Japan.


(Leventhall, 2003) Mirowska and Mroz (Mirowska/Mroz, 2000) conducted one specific survey based on health effects of low frequency noise from plants and appliances, in or near domestic buildings in 2000, as shown in table 2 (Leventhall, 2003, p.49), their measured level and frequency of occurrence.


A control group of dwellings were compared with similar test dwellings that had low frequency noise and the most remarkable difference in the two groups were psychological effects (although there are physiological ones in both groups, as shown in table 3 (Leventhall, 2003, pg.49)) such as depression and frustration which clearly shows that the test group could not displace the annoying noise that was leading them to be more inclined to depression and anxiety.


In 2003, the Department of Environment, Food and Rural Affairs (DEFRA) conducted a survey where they distributed forms to people who had formed pressure groups against low frequency noise (commonly referred to as “the Hum”) such as the Low Frequency Noise Sufferers Association, the Noise Abatement Society or the UK Noise Association.


Based on their authenticity, it was found that there was an increase in the number of people susceptible to low noise annoyance as age ranges went up, with almost none of the complainants being below 25. The most notable findings of this study were the facts that most people heard this sound in the form of a “hum”, “pulsing” or “buzzing” almost all the time and mostly in and around their homes.


Some people claimed to know the sources such as traffic, heavy machinery, power plants; transformers etc. while some could not put a finger on it. Few of the respondents had become accustomed to the sound even, no longer disturbed or annoyed by its constant presence. The cause for most of the physiological effects in subjects cannot be pinpointed to Infrasound, therefore a full clinical examination and assessment of subjects needs to be undertaken to exclude any other primary or secondary cause.


All these surveys show strikingly parallel results in both, the psychological and physiological spheres and direct the scientific community towards a better understanding. Controlled laboratory experiments on rats, mice, chinchilla and guinea pigs, experiments in vitro to study the effect of Infrasound at a cellular level, provide us with critical information about the possible effects of Infrasound on our bodily processes.


The results of some animal studies reporting adverse effects from infrasound exposure (such as published in the Infrasound Toxicological Summary, 2001, increases in systolic and diastolic pressure (Pei et al, 2007); increases in glutamate concentration in rat brain (Guo-You et al, 1999); a significant drop in dopamine and norepinephrine concentrations in rat brain (Spyraki et al, 1980); increased latency to avoid and escape (Petounis et al, 1977); ruptured blood vessel walls and induced 7 cellular hypertrophy in the lungs of mice (Svidovyi and Glinchikov,1987)) may be relevant for indicating possible human health effects, but for the purposes of this text, the focus will be on the studies on human test subjects.


Although there is a lack of intensive research on the biological effects of exposure to long-term high/low intensity Infrasound, many studies have suggested that the alleged effects to physiology are not true. For example, in a study by (Johnson, 1975) “an investigator stood on one leg with his eyes closed, listening aurally to 165dB at 7Hz and 172dB at 1 to 8Hz (frequency sweep) without effect.”


On the other hand, in a study by Tagikawa et al, where when exposed to 5 and 16 Hz at 95 dB for 5 minutes, subjects showed altered body sway responses suggesting effects on the vestibular system and balance. (Lidstrom, 1978) discovered that on long-term exposure to Infrasound (14 or 16 Hz at 125 dB), aircraft pilots were less alert and their hearing threshold and time perception were temporarily challenged.


Military procedure recognizes this factor, and routinely limits flight time. It is known that excess infrasonic exposures endanger pilots and their flight missions. Conversely, in order to understand changes in cognitive performance under exposure of Infrasound (7 Hz tones at 125, 132, and 142dB plus ambient noise or a low frequency noise up to 30 minutes), (Harris and Johnson, 1978) observed no decline in performance.


Evans (Evans and Tempest, 1972) examining the effect of infrasonic environments on human behavior, found that 30% of normal subjects exposed to tones of 2 - 10Hz through earphones at SPLs of 120 – 150 dB had nystagmus (involuntary eye movements) within 60 seconds of exposure to the 120dB signal, with 7Hz being most effective in causing it. The onset of nystagmus was quicker when the intensities were increased, although none of the subjects complained of any discomfort at any SPL.


(Danielsson and Landstrom, 1985) recorded increased diastolic and decreased systolic pressure without change in pulse rate in 20 healthy male volunteers exposed to varying frequencies (6, 12, 16 Hz) and SPLs (95, 110, 125 dB) for 30 minutes.


All the above studies have been compiled from published reports (Leventhall, 2003; Infrasound Toxicological Summary, 2001; Health Protection Agency, 2010).


It has to be understood that most of the annoyance caused by Infrasound is nothing without low frequency noise adding to our perception of natural noise, and this noise is what people blame for disturbing their sleep pattern.


According to the WHO Guide for Community Noise, the primary sleep disturbance effects are: difficulty in falling asleep (increased sleep latency time); awakenings; and alterations of sleep stages or depth, especially a reduction in the proportion of REM-sleep (REM = rapid eye movement) (Hobson 1989).


Other primary physiological effects can also be induced by noise 8 during sleep, including increased blood pressure; increased heart rate; increased finger pulse amplitude; vasoconstriction; changes in respiration; cardiac arrhythmia; and an increase in body movements (cf. Berglund & Lindvall 1995). For each of these physiological effects, both the noise threshold and the noise-response relationships may be different.


Different noises may also have different information content and this also could affect physiological threshold and noise-response relationships (Edworthy 1998). Most of the scientific community discounts fatigue, drowsiness and sleepiness as being the relaxation effects of Infrasound vibrations (perceived by the body and not the ear), rather than any adverse health effect.


Going back to case of “Building sickness” that Gavreau et al experienced, it could be stated that they might have been under prolonged exposure to Infrasound vibrations, therefore the nauseating feeling has never been proved to be correct, as such experiments have not been replicated/reported.


All these and many such studies are based on low intensity exposure because the cost of deafening a subject or subjecting them to severe discomfort in high intensity low frequency fields (even low intensity, long-term for that matter), for the sake of discovery, would be unethical.


Intense low frequency noise and Infrasound together have been clearly known to cause aural pain and damage, as in the case of blasts, mining and space shuttle launches/heavy weapon testing.


In conclusion of this chapter, it has been shown that all the adverse alleged effects of Infrasound, have been disproved or discounted by the scientific community as pseudo-science or sensationalized assumptions, and until further work proves otherwise, it can be said that Infrasound, as we know it and perceive it, is fairly harmless.



A speculative analysis of possible weaponry

Strong sounds can be produced using loudspeakers connected to amplifiers, although, to produce low frequencies at loud enough levels, very large arrays of loudspeakers with large diameter horns (since the wavelength of Infrasound is greater that 20m) would be required along with huge combustion engines to power the amplifiers and loudspeaker arrays (Stark, 2008, p.210).


This is one of the major reasons why Infrasonic weapons in the battlefield would be unfeasible and cumbersome. Table 6 lists some possible sources to produce high intensity sound though not specifically Infrasound.


Dr. Jurgen Altmann, in his intensive study Acoustic Weapons: A Prospective Assessment, tries to demystify the theories referring to Infrasound weapons in journalistic articles. For instance, he points out that Infrasound 9 cannot be harnessed into a beam, therefore debunking the myth that Infrasound weaponry can be directed at targets.


The reasons for this can be clearly pointed to the well know fact that low frequency sounds radiate spherically from a source as the wavelength is larger than the source in physical size (and even if we were able to build a large enough sound system, due to the inherent nature of the low frequency it would radially disperse after projection from the source) and also to the fact that the intensity drops exponentially (6 dB for every doubling of distance).


Therefore the discomfort caused by such an installation would only affect people in the immediate vicinity (aural pain and damage from short-term exposure is expected—in case of unprotected hearing—for distances up to a few meters), who could voluntarily move away from such a stationary source.


The allegations that Infrasound alone can be used to demolish buildings (like an earthquake), stands on shaky ground, as this largely depends on the association of the infrasonic frequency and the resonant character of the space it is coupled with, to cause such a drastic impact. The resonance produced within the building would be the reason for any vibrations (damaging or otherwise) within the building and not just Infrasonic force.


One of the journalistic articles suggested that Russia had developed a weapon that produces non-diffracting, basketball sized, 10 Hz bullets. Upon a closer inspection, this statement contradicts itself as a 10 Hz signal implies a wavelength of 34 m; not quite a basketball sized wave packet.


Also, due to the radial propagation of waves from the source, operating personnel would be exposed to potentially damaging effects. It becomes clear from the information thus presented that Infrasound may not be feasible as an assault weapon but would rather be used in weapons system applications which do not require directing the sound or do not require the effects to propagate beyond a certain perimeter.


Some foreseeable applications therefore, budding from present technology, could be area denial in high security facilities, or area attack such as clearing out a building to search it without any casualties or in a hostage situation, protecting environmental assets by deterring animals and birds from crossing into potentially hazardous urban environments such as motorways, waste disposal and landfills, airports, wind farms etc.


Animals, due to a lack of communication skills possessed by humans, rely heavily on the tonal content of their surroundings. The loud, high-pitched sound of the females and young ones makes them a natural target to predators whereas the low, rumbling, guttural sound produced by males in most species makes them elusive as the predator cannot pin point the location of the male.


Low pitched tones cling to the ground and cause the animals to be anxious, as if sensing an impending doom, and it is common knowledge 10 now, that animals are good predictors of natural calamities.


Infrasound, though not effective as an audible force, does not lose propagation intensity along the ground as much as it does in the air. (Vasillatos, 1992) uses this information as an analogy that could be used in future Infrasound weapons systems, mostly based on the alleged weapons hypothesized by Gavreau. It is a known fact that Infrasound hugs the ground and therefore would put the life of the operators in peril.


Systems used to overcome this problem would require further research and development in the fields of structural engineering (in order to create efficient absorbent baffles around the source that would, if not completely nullify, at least reduce the effect of Infrasound in and around the effective radiating area), robotics (such that a remote controlled Infrasound generator could be operated form a distance without any collateral damage) etc.


Moreover, he points out in the work of Gavreau, that certainly for a weapon, the effects of which cannot be ascertained by our perception until the time it strikes, there would be the need of Infrasound detectors. There is also the idea that to have an effective responsive Infrasound annulment weapons systems would be beneficial for any nation looking to build such weapons, as it could use the wave physics principal of negative interference to cancel or at least reduce the levels of incoming Infrasound waves, as a form of protection against Infrasound.


This method would require high speed detection and response systems that would determine the pitch and intensity of the incoming wave, generate that waveform and project it out of phase.



Inference

All these applications are highly hypothetical and would only have any practical application based on socio-political, technological and ethical factors along with feasibility of operation/production.


At this juncture in humanities progress, we can only hope, that the powers that be, propel this energy in the direction it would best be used in an interdisciplinary ideology for the benefit of humankind, examples of which are slowly beginning to mushroom and grow into our lives, and not just focus on the life threatening aspects of this energy form.



Bibliography

Books


  • Cerasini, Marc, 2002, The Future of War, Pearson Education Inc.

  • McNeill, William H., 1984, The Pursuit of Power, University of Chicago Press.

  • Stark, S.H., 2008, Live Sound Reinforcement, Course Technology PTR.

  • White, Michael, 2005, The Fruits of War, Simon & Schuster UK ltd.


Online Sources





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