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Hearing of microwave pulses by humans and animals: Effects, mechanism, and thresholds
Abstract
The hearing of microwave pulses is a unique exception to the airborne or bone-conducted sound energy normally encountered in human auditory perception. The hearing apparatus commonly responds to airborne or bone-conducted acoustic or sound pressure waves in the audible frequency range. But the hearing of microwave pulses involves electromagnetic waves whose frequency ranges from hundreds of MHz to tens of GHz. Since electromagnetic waves (e.g., light) are seen but not heard, the report of auditory perception of microwave pulses was at once astonishing and intriguing. Moreover, it stood in sharp contrast to the responses associated with continuous-wave microwave radiation. Experimental and theoretical studies have shown that the microwave auditory phenomenon does not arise from an interaction of microwave pulses directly with the auditory nerves or neurons along the auditory neurophysiological pathways of the central nervous system. Instead, the microwave pulse, upon absorption by soft tissues in the head, launches a thermoelastic wave of acoustic pressure that travels by bone conduction to the inner ear. There, it activates the cochlear receptors via the same process involved for normal hearing. Aside from tissue heating, microwave auditory effect is the most widely accepted biological effect of microwave radiation with a known mechanism of interaction: the thermoelastic theory. The phenomenon, mechanism, power requirement, pressure amplitude, and auditory thresholds of microwave hearing are discussed in this paper. A specific emphasis is placed on human exposures to wireless communication fields and magnetic resonance imaging (MRI) coils.
... T HE microwave auditory effect pertains to the hearing of pulse-modulated microwave energy at high peak power by humans and laboratory animals [1]- [3]. It has been widely recognized as one of the most interesting and significant biological phenomena from microwave exposure [4]- [7]. The hearing of pulsed microwaves or audible microwaves is a unique exception to the sound energy, normally encountered in human auditory perception. ...
... The thermoelastic theory has been shown as the most effective mechanism since pressures generated by thermoelastic stress are two to three orders of magnitude greater than by any other proposed mechanisms [3], [4], [6], [7]. ...
... A generalization of the methodology, again using a homogeneous sphere head model but with an arbitrary SAR pattern of spherical symmetry, has also been reported [59]. More precise computer simulations of the properties of microwave-pulse-induced sound pressure wave using realistic anatomic head models have also been conducted [7], [58], [60]- [62]. ...
The microwave auditory effect has been widely recognized as one of the most interesting and significant biological phenomena from microwave exposure. The hearing of pulsed microwaves is a unique exception to sound waves encountered in human auditory perception. The hearing of microwave pulses involves electromagnetic waves. This paper reviews the research in humans and animals leading to scientific documentations that absorption of a single microwave pulse impinging on the head may be perceived as an acoustic zip, click, or knocking sound. A train of microwave pulses may be sensed as buzz, chirp, or tune by humans. It describes neurophysiological, psychophysical, and behavioral observations from laboratory studies involving humans and animals. Mechanistic studies show that the microwave pulse, upon absorption by tissues in the head, launches a pressure wave that travels by bone conduction to the inner ear, where it activates the cochlear receptors via the same process involved for normal sound hearing. Depending on the impinging microwave pulse powers, the level of induced sound pressure could be considerably above the threshold of auditory perception to cause tissue injury. The microwave auditory effects and associated pressures could potentially render damage to brain tissue to cause lethal or nonlethal injuries.
... While our findings address unsolved challenges in assessing direct effects of continuous-wave RF exposure in vivo, they do not exclude potential responses to pulsed RF stimulation using very high power short-time RF pulses. Short (10-100 µs) high energy RF pulses induce sound perception in both humans and experimental animals 61,62 . Because the estimated temperature changes associated with such short pulses are only on the order of 10 −6 o C 62 , it has been suggested that vibration-mediated thermos-elastic effects in brain tissue are the principal mediating effect [62][63][64] . ...
... Short (10-100 µs) high energy RF pulses induce sound perception in both humans and experimental animals 61,62 . Because the estimated temperature changes associated with such short pulses are only on the order of 10 −6 o C 62 , it has been suggested that vibration-mediated thermos-elastic effects in brain tissue are the principal mediating effect [62][63][64] . In addition, subsequent experiments in cats (918 or 2450 MHz) showed that destruction of the cochlea eliminated the brain evoked potentials, suggesting that the audible clicking sensations are due to mechanical vibration 65,66 , similar to indirect ultrasound pulse-induced effects 67,68 . ...
... Short (10-100 µs) high energy RF pulses induce sound perception in both humans and experimental animals 61,62 . Because the estimated temperature changes associated with such short pulses are only on the order of 10 −6 o C 62 , it has been suggested that vibration-mediated thermos-elastic effects in brain tissue are the principal mediating effect [62][63][64] . In addition, subsequent experiments in cats (918 or 2450 MHz) showed that destruction of the cochlea eliminated the brain evoked potentials, suggesting that the audible clicking sensations are due to mechanical vibration 65,66 , similar to indirect ultrasound pulse-induced effects 67,68 . ...
As the use of Radio Frequency (RF) technologies increases, the impact of RF radiation on neurological function continues to receive attention. Whether RF radiation can modulate ongoing neuronal activity by non-thermal mechanisms has been debated for decades. However, the interactions between radiated energy and metal-based neural probes during experimentation could impact neural activity, making interpretation of the results difficult. To address this problem, we modified a miniature 1-photon Ca2+ imaging device to record interference-free neural activity and compared the results to those acquired using metal-containing silicon probes. We monitored the neuronal activity of awake rodent-brains under RF energy exposure (at 950 MHz) and in sham control paradigms. Spiking activity was reliably affected by RF energy in metal containing systems. However, we did not observe neuronal responses using metal-free optical recordings at induced local electric field strengths up to 230 V/m. Our results suggest that RF exposure higher than levels that are allowed by regulatory limits in real-life scenarios do not affect neuronal activity. Omid Yaghmazadeh and colleagues explore non-thermal responses to RF radiation in live rodent brains using electrophysiology and 1-photon Ca2+ imaging. They saw no impact of RF energy in metal-free recordings at levels higher than regulatory limits.
... In particular, the local temperature around such particles can be increased stronger. A standard argumentation [39,40] that a temperature increase by 10 −4 − 10 −5 • C is physically and biologically irrelevant is wrong, as evidenced by the theory and practice of microwave auditory effect [13,15]. This is because the temperature increase is very rapid at a pulse-modulation. ...
... Nevertheless, there is a huge body of evidence of a substantial impact ( [1][2][3][4], see, especially, the book by Binhi [5] and the references therein). One of such manifestations is given by the microwave auditory effect or Allan Frey hearing effect [6][7][8][9][10][11][12][13][14][15][16], an auditory perception of microwave pulses by humans and animals, which earlier has been considered mysterious. Now, the mystery of this effect is completely resolved within a thermoelastic theory [7][8][9][10][11][12][13][14][15][16] of acoustic wave production in closed resonators (e.g., human or animal head) filled with microwave absorbing tissues having a very large water content (think about heating of food in microwave oven, to realize a possible physical reason). ...
... One of such manifestations is given by the microwave auditory effect or Allan Frey hearing effect [6][7][8][9][10][11][12][13][14][15][16], an auditory perception of microwave pulses by humans and animals, which earlier has been considered mysterious. Now, the mystery of this effect is completely resolved within a thermoelastic theory [7][8][9][10][11][12][13][14][15][16] of acoustic wave production in closed resonators (e.g., human or animal head) filled with microwave absorbing tissues having a very large water content (think about heating of food in microwave oven, to realize a possible physical reason). Good reviews are available [13][14][15] and the theory and experiment agree convincingly well. ...
[-15]Magnetic nanoparticles are met across many biological species ranging from magnetosensitive bacteria, fishes, bees, bats, rats, birds, to humans. They can be both of biogenetic origin and due to environmental contamination, being either in paramagnetic or ferromagnetic state. The energy of such naturally occurring single-domain magnetic nanoparticles can reach up to 10-20 room k B T in the magnetic field of the Earth, which naturally led to supposition that they can serve as sensory elements in various animals. This work explores within a stochastic modeling framework a fascinating hypothesis of magnetosensitive ion channels with magnetic nanoparticles serving as sensory elements, especially, how realistic it is given a highly dissipative viscoelastic interior of living cells and typical sizes of nanoparticles possibly involved.
... Sound. Hissing, buzzing or fluttering sounds from ball lightning have been reported, which can be perfectly explained by the microwave hearing effect 48,49 . At 0.1 mJ/cm 2 , a microwave pulse (microsecond or shorter) at 0.2-3 GHz can induce an audible sound wave. ...
... Microwave can penetrate deeply into the tissue and cause an influence by thermal effects. Microwave hearing 48,49,56 is the lowest power effect on humans and occurs when the absorbed energy in the brain tissue reaches 10 μJ/g for a 10 μs pulse. For a typical adult brain with 14 cm in diameter and 1.4 kg in weight, we get an energy flux threshold of 0.1 mJ/cm 2 . ...
... For a typical adult brain with 14 cm in diameter and 1.4 kg in weight, we get an energy flux threshold of 0.1 mJ/cm 2 . Experiments 48,49 show this hearing effect induced by 0.2-3 GHz microwave pulses with 1− 100 μs in duration. Theoretical analysis reveals that rapid (~μs) temperature rise (~10 −6 degree) leads to a thermoelastic expansion of tissue, which launches an acoustic wave travelling by the skull to the inner ear. ...
Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.
... If the reported accounts are consistent, the microwave auditory effect provides a scientific explanation for the Havana syndrome. Pulsed microwaves can create an acoustic pressure wave inside the head, remotely [9]- [11]. It is plausible that the loud buzzing, burst of sound, or pressure sensation could have been covertly delivered using a directed beam of high-power pulsed microwave radiation. ...
... Absorption of short (µs, microsecond wide) pulses of microwave energy by brain tissues is known to create a rapid elastic expansion of brain matter and launches an acoustic wave of pressure (sound wave) that travels inside the head to the inner ear [9]- [11]. Once there, it activates the hair-cell neuronal sensors in the cochlea, which then relays the neural signal to the central auditory system for sound perception, via the same central process involved in normal hearing. ...
The mysterious incidents on diplomatic and intelligence personnel began in 2016. Since then, nearly 200 incidents have been reported. The illnesses and symptoms are called Havana Syndrome, named for the city where cases were first reported. The initial accounts from Havana include hearing of loud high-pitched sounds, localizing the sources as coming from above or behind the head, experiencing a directional sound that ceases if one steps away, the covering of ears not making any difference, some hearing the sound but others in the same room not hearing it, or hearing it in one part of a room but not in other areas. Assuming the reported symptoms and accounts are consistent, the microwave auditory effect provides a scientific explanation for Havana Syndrome.
... In addition to field experiments, we also conducted laboratory experiments in order to assess potential vessel permeabilization in exposed animals. Intense electric field pulses may increase the permeability of blood vessels [10,17]. While this effect has not been ascertained in vivo [18], it has been suggested that 1.8 GHz GSM-like electromagnetic fields might increase the permeability of the blood-brain barrier in in vitro models [19]. ...
... The superficial tissue was surgically removed, leaving a facial plane with associated vasculature. Ensuing the surgery and the following day, a non-steroidal anti-inflammatory agent (Profenid, Sanofi-Aventis, Paris, France) was injected intramuscularly (10 mg/kg, 50 µL in each thigh), to provide analgesia and to avoid inflammation [10,17]. ...
High power radiofrequencies may transiently or permanently disrupt the functioning of electronic devices, but their effect on living systems remains unknown. With the aim to evaluate the safety and biological effects of narrow-band and wide-band high-power electromagnetic (HPEM) waves, we studied their effects upon exposure of healthy and tumor-bearing mice. In field experiments, the exposure to 1.5 GHz narrow-band electromagnetic fields with the incident amplitude peak value level in the range of 40 kV/m and 150 MHz wide-band electric fields with the amplitude peak value in the range of 200 kV/m, did not alter healthy and tumor-bearing animals’ growth, nor it had any impact on cutaneous murine tumors’ growth. While we did not observe any noticeable behavioral changes in mice during the exposure to narrow-band signals when wide-band HPEM signals were applied, mice could behave in a similar way as they respond to loud noise signals: namely, if a mouse was exploring the cage prior to signal application, it returned to companion mates when wide-band HPEM signals were applied. Moreover, the effect of wide-band signals was assessed on normal blood vessels permeability in real-time in dorsal-chamber-bearing mice exposed in a pilot study using wide-band signal applicators. Our pilot study conducted within the applicator and performed at the laboratory scale suggests that the exposure to wide-band signals with the amplitude of 47.5 kV/m does not result in increased vessel permeability.
... It employs microwave pulse-induced thermoelastic pressure waves to form planar or tomographic images of biological tissues. The modality is based on the observation that sonic and ultrasonic waves can be generated in biological tissues by direct deposition of short high-power microwave pulses (Lin 1977a(Lin , 1977b(Lin , 1980(Lin , 2007. The absorption of pulsed microwave energy causes a rapid (∼μs) rise in tissue temperature (∼10 −6°C ). ...
... The microwave auditory effect or the hearing of microwavepulseinduced sound involves a cascade of events. The neurophysiology, behavioral characteristics, auditory thresholds, and the thermoelastic mechanism of transduction of pulsed microwave-induced acoustic pressure waves in humans and animals are given in published reviews (Lin 1980, Elder and Chou 2003, Lin and Wang 2007. The recognition of the propagation nature of the acoustic wave of pressure in biological tissues prompted the exploration of its potential for application in biological and medical imaging (Lin 1982, Olsen 1982, Lin and Chan 1983, Olsen and Lin 1983. ...
Microwave thermoacoustic tomography (MTT) uses microwave-pulse-induced thermoelastic pressure waves to form planar or tomographic images. Since the generation and detection of thermoelastic pressure waves depends on dielectric permittivity, specific heat, thermal expansion, and acoustic properties of tissue, microwave thermoacoustic imaging possesses the characteristic features of a duel-modality imaging system. The unique attributes of the high contrast offered by microwave absorption and the fine spatial resolution furnished by ultrasound are being explored to provide a nonionizing and noninvasive imaging modality for characterization of tissues, especially for early detection of breast cancer. This paper reviews the research being conducted in developing MTT imaging for medical diagnosis. It discusses the science of thermoelastic wave generation and propagation in biological tissues, the design of prototype MTT systems, the reconstruction of tomographic images, and the application and accomplishment of prototype MTT systems in phantom models and experimental subjects.
... His detailed descriptions were designated as the Frey Effect (22). Subsequently, Lin et al. (23) clarified the fact that square microwave pulses are audible. Experimental modeling determined that the microwave pulse rapidly heats tissue in the "skin" brain depth (depth of 1/2.7 of incident energy). ...
... Figure 2 shows that 0.3-10 GHz microwave radiation penetrates a few cm to a few mm into brain tissue. The resulting thermal expansion may launch an acoustic wave by thermoelastic effect traveling by bone conduction to the inner ear where it activates cochlear receptors (23). A single microwave pulse may thus be perceived as an acoustic click while a train of microwave pulses is sensed as an audible tone with a pitch corresponding to the pulse repetition rate. ...
Pulsed microwaves above specific energy thresholds have been reported to cause brain injury in animal models. The actual physical mechanism causing brain damage is unexplained while the clinical reality of these injuries remains controversial. Here we propose mechanisms by which pulsed microwaves may injure brain tissue by transduction of microwave energy into damaging acoustic phonons in brain water. We have shown that low intensity explosive blast waves likely initiate phonon excitations in brain tissues. Brain injury in this instance occurs at nanoscale subcellular levels as predicted by physical consideration of phonon interactions in brain water content. The phonon mechanism may also explain similarities between primary non-impact blast-induced mild Traumatic Brain Injury (mTBI) and recent clinical and imaging findings of unexplained brain injuries observed in US embassy personnel possibly due to directed radiofrequency radiation. We describe experiments to elucidate mechanisms, RF frequencies and power levels by which pulsed microwaves potentially injure brain tissue. Pathological documentation of nanoscale brain blast injury has been supported experimentally using transmission electron microscopy (TEM) demonstrating nanoscale cellular damage in the absence of gross or light microscopic findings. Similar studies are required to better define pulsed microwave brain injury. Based upon existing findings, clinical diagnosis of both low intensity blast and microwave-induced brain injury likely will require diffusion tensor imaging (DTI), a specialized water based magnetic resonance imaging (MRI) technique.
... Pero la hipersensibilidad a los campos electromagnéticos no sería un prerrequisito para su detección [14]. Por otro lado, se han planteado que las diferencias encontradas son resultado de las creencias y pensamientos de las diferentes personas acerca de los efectos de los campos electromagnéticos en la salud [12]. Otra hipótesis es la preexistencia de condiciones psiquiátricas, o la presencia de rasgos de personalidad hipocondríacos. ...
... Existen evidencias de que la exposición a campos electromagnéticos ya sea durante y después de la misma, se asocian a cambios fisiológicos cerebrales. Por ejemplo, breves exposiciones pueden inducir cambios en la actividad eléctrica cerebral, sobre todo en la banda de la frecuencia alfa (8)(9)(10)(11)(12)(13). Se han registrado cambios en la memoria de reconocimiento tras la exposición a 100 μT durante 1 segundo, así como disminución de la actividad alfa en corteza occipital, tras exposiciones de 15 min a 80 μT [1]. ...
Algunos aspectos de la conducta ecológica y la percepción de riesgos ambientales relacionados con los campos electromagnéticos se consideran brevemente desde las perspectivas biomédica y psicosocial en el marco de las interacciones entre los tres mundos: Umwelt, Mitwelt, Eigenwelt. Se menciona parte de la evidencia disponible y se discuten algunas de las dificultades que deben afrontar tanto los investigadores como los gestores que se ocupan de los efectos biológicos, psicológicos y sociales de la exposición a los campos electromagnéticos.
Palabras clave: Umwelt, Mitwelt, Eigenwelt, campos electromagnéticos y conducta, psico-neuro-inmuno-endocrinología, conducta ecológica, percepción de riesgos ambientales, marco sociocultural.
Abstract: Some issues of ecological behaviour and environmental risk perception related with electromagnetic fields are briefly considered from biomedical and psychosocial points of view in the framework of the interaction of the three worlds: Umwelt, Mitwelt, Eigenwelt. Some available evidence related with the biological, psychological and social effects of the exposure to electromagnetic fields is mentioned and some difficulties that researchers and managers must face are discussed.
Key words: Umwelt, Mitwelt, Eigenwelt, electromagnetic fields and behaviour, psico-neuro-immuno-endocrinology, ecological behaviour, environmental risk perception, socio-cultural framework.
... It then stimulates the cochlear receptors in the same way as natural hearing does. 26 Since cell phones commonly use the Wi-Fi frequency alongside the GSM frequency, the impact of Wi-Fi on the ear has become a question worth investigating. According to our findings, apoptosis increases in the inner ear as the EMF increases. ...
Background
The present study aims to determine the possible low dose-dependent adverse effects of 2.45 GHz microwave exposure and Wi-Fi frequency on the cochlea.
Methods
Twelve pregnant female rats (n = 12) and their male newborns were exposed to Wi-Fi frequencies with varying electric field values of 0.6, 1.9, 5, 10 V/m, and 15 V/m during the 21-day gestation period and 45 days after birth, except for the control group. Auditory brainstem response testing was performed before exposure and sacrification. After removal of the cochlea, histopathological examination was conducted by immunohistochemistry methods using caspase (cysteine-aspartic proteases, cysteine aspartates, or cysteine-dependent aspartate-directed proteases)-3, -9, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). Kruskal–Wallis and Wilcoxon tests and multivariate analysis of variance were used.
Results
Auditory brainstem response thresholds in postexposure tests increased statistically significantly at 5 V/m and above doses. When the number of apoptotic cells was compared in immunohistochemistry examination, significant differences were found at 10 V/m and 15 V/m doses (F (5,15) = 23.203, P = .001; Pillai’s trace = 1.912, η ² = 0.637). As the magnitude of the electric field increased, all histopathological indicators of apoptosis increased. The most significant effect was noted on caspase-9 staining (η ²c9 = 0.996), followed by caspase-3 (η ²c3 = 0.991), and TUNEL staining (η ²t = 0.801). Caspase-3, caspase-9, and TUNEL-stained cell densities increased directly by increasing the electric field and power values.
Conclusion
Apoptosis and immune activity in the cochlea depend on the electric field and power value. Even at low doses, the electromagnetic field in Wi-Fi frequency damages the inner ear and causes apoptosis.
... Overall, our experiments indicate that RF effects on excitable tissue are mediated primarily by transient or sustained heat. Yet, we cannot conclusively exclude previously postulated nonthermal effects of RF irradiation, such as vibrationmediated thermo-elastic effects in brain tissue (Chou & Guy, 1979;Chou et al., 1982;Lin & Wang, 2007). ...
Over the past few decades, daily exposure to radiofrequency (RF) fields has been increasing due to the rapid development of wireless and medical imaging technologies. Under extreme circumstances, exposure to very strong RF energy can lead to heating of body tissue, even resulting in tissue injury. The presence of implanted devices, moreover, can amplify RF effects on surrounding tissue. Therefore, it is important to understand the interactions of RF fields with tissue in the presence of implants, in order to establish appropriate wireless safety protocols, and also to extend the benefits of medical imaging to increasing numbers of people with implanted medical devices. This study explored the neurological effects of RF exposure in rodents implanted with neuronal recording electrodes. We exposed freely moving and anesthetized rats and mice to 950 MHz RF energy while monitoring their brain activity, temperature, and behavior. We found that RF exposure could induce fast onset firing of single neurons without heat injury. In addition, brain implants enhanced the effect of RF stimulation resulting in reversible behavioral changes. Using an optical temperature measurement system, we found greater than tenfold increase in brain temperature in the vicinity of the implant. On the one hand, our results underline the importance of careful safety assessment for brain-implanted devices, but on the other hand, we also show that metal implants may be used for neurostimulation if brain temperature can be kept within safe limits.
... There seems to be an association between subjective electrohypersensitivity and tinnitus which may have been perpetuated due to overactivated cortical distress networks in the vulnerable human population [64]. Humans and animals hear clicks or other sounds when exposed to short pulse (1-20 μsec) microwave RF [92]. A study in 1962 revealed that different types of field are perceived as different sounds like buzzing, ticking, hissing, or knocking sounds [93]. ...
Even before the wake of this global pandemic and the associated social distancing norms, the lives of human beings cannot
be imagined without cellular phones and electronic gadgets and the probability to be exposed to their harmful radiations is
inevitable to an astounding extent in both adults, working from home and children, dependent on online classes and exams.
Electro-pollution is skyrocketing and its impact can be perceived particularly as electro-hypersensitivity among human beings,
penetrating even on deeper cellular and genetic levels. Advent of 5G technology will add on to the pre-existing radiation exposure
at ambient and individual levels. Safety limits of exposure to electromagnetic radiation, as advised by responsible agencies/
authorities, protects the industry and neglects human health and environmental homeostasis. This review critically analyzed
the records of the development of mobile communication technologies, the associated electromagnetic fields and frequencies
and the neuronal health issues emerging due to their sustained, yet, fluctuating presence throughout the three decades since
inception. It highlights the precautions to be taken meanwhile and the need for extensive future research in this aspect to prevent
such perturbations affecting our daily lives and the environment.
... Nevertheless, it can launch an acoustic wave of pressure that travels inside the head to the inner ear. There, it activates the hair-cell nerves in the cochlea, which then relay it to the central auditory system for perception, via the same process involved in normal sound hearing [3][4][5][6]. ...
As I write this article, the US National Academies of Sciences, Engineering, and Medicine (NASEM) have just released their study report on “An Assessment of Illness in U.S. Government Employees and Their Families at Overseas Embassies” [1]. It has been about three years since the publication of my article describing the mystery of sonic health attacks on Havana-based diplomats [2]. It was first hypothesized in this paper, assuming that the reported events were reliable, that there was actually a scientific explanation for the source of sonic energy. It could well have been “from a targeted beam of high-power microwave pulse radiation.”
... The avoidance did not correlate with insect abundance Racey 2007, 2009). There is no known interaction with the magnetic sense at this frequency; instead it is hypothesized that the animals hear (microwave hearing; Lin and Wang 2007) or thermally perceive the radar pulses close to the transmitter. ...
This report summarizes the effects of anthropogenic radiofrequency electromagnetic fields with frequencies above 100 MHz on flora and fauna presented at an international workshop held on 5–7 November 2019 in Munich, Germany. Anthropogenic radiofrequency electromagnetic fields at these frequencies are commonplace; e.g., originating from transmitters used for terrestrial radio and TV broadcasting, mobile communication, wireless internet networks, and radar technologies. The effects of these radiofrequency fields on flora, fauna, and ecosystems are not well studied. For high frequencies exceeding 100 MHz, the only scientifically established action mechanism in organisms is the conversion of electromagnetic into thermal energy. In accordance with that, no proven scientific evidence of adverse effects in animals or plants under realistic environmental conditions has yet been identified from exposure to low-level anthropogenic radiofrequency fields in this frequency range. Because appropriate field studies are scarce, further studies on plants and animals are recommended.
... Overall, our experiments indicate that RF effects on excitable tissue are mediated primarily by transient or sustained heat. Yet, we cannot conclusively exclude previously postulated non-thermal effects of RF irradiation, such as vibration-mediated thermo-elastic effects in brain tissue [58][59][60] . ...
Over the past few decades, daily exposure to radiofrequency (RF) fields has been increasing due to the rapid development of wireless and medical imaging technologies. Under extreme circumstances, exposure to very strong RF energy can lead to heating of body tissue, even resulting in tissue injury. The presence of implanted devices, moreover, can amplify RF effects on surrounding tissue. Therefore, it is important to understand the interactions of RF fields with tissue in the presence of implants, in order to establish appropriate wireless safety protocols, and also to extend the benefits of medical imaging to increasing numbers of people with implanted medical devices. This study explored the neurological effects of RF exposure in rodents implanted with neuronal recording electrodes. We exposed freely moving and anesthetized rats and mice to 950 MHz RF energy while monitoring their brain activity, temperature, and behavior. We found that RF exposure could induce fast onset firing of single neurons without heat injury. In addition, brain implants enhanced the effect of RF stimulation resulting in reversible behavioral changes. Using an optical temperature measurement system, we found greater than tenfold increase in brain temperature in the vicinity of the implant. On the one hand, our results underline the importance of careful safety assessment for brain implanted devices, but on the other hand, we also show that metal implants may be used for neurostimulation if brain temperature can be kept within safe limits.
... Occasional/possible altered cortical excitability 534 535 auditory sensitivity 536 chemical sensitivity 537 538 539 light sensitivity 540 microwave/RF hearing, tinnitus 541 542 543 544 545 546 547 (odontological) metallic sensitivity 548 549 550 persitent organic pollutants 551 skin symptoms, rosacea 552 553 554 555 chronic fatigue syndrome 556 dental hyperalgesia 557 dry eye syndromes 558 epileptic episodes, migraine 559 560 561 562 polymorphic dystonia 563 restless leg syndrome 564 565 thyroid dysfunction and liver dysfunction 566 Tourette's, blepharospasm 567 Associations between disease (other than EHS) and EMFs Extremely Low Frequency (ELF) 30 568 "possibly carcinogenic", WHO: IARC, 2011 ALS 569 570 571 572 573 574 Alzheimer's 575 576 577 578 childhood leukaemia 579 580 581 582 583 584 585 586 587 cancers, primary 588 brain 589 590 breast 591 592 593 594 595 596 mal. melanoma 597 prostate 598 testicular 599 cardiovasc. ...
Electromagnetic Hypersensitivity is categorised as a multisymptomatic 'el-allergy' in the Nordic classification of 2000 (R.68.8). Its symptoms are 'certainly real' and it can be a 'disabling condition' (W.H.O., 2005). It was first recorded in the mid 20th century as an occupational illness, but it has now spread into the general population through environmental exposure from increasing levels of electromagnetic fields and radiation.
This Summary covers current research on this syndrome, covering EM Sensitivity and EM Hypersensitivity. It includes tables of symptoms, EMF sources and exposure guidelines, along with references to scientific studies.
This New Edition adds updates, international doctors' protocols, aspects of quantum biology, evidence for sensitivity in animals and plants, case studies, disability issues and human rights.
... Although equivalent research has not been conducted in humans, and although there remains the possibility that different TRP receptors are involved, there is currently no evidence that direct activation of thermoreceptors by RF-EMFs is responsible for the above thermoregulatory changes. Another possibility is that the effect on the EEG is related to the wellestablished microwave hearing effect, where brief (circa 100 μs), low-level (circa 5 mJ) RF-EMF pulses cause thermoelastic expansion that travels as a wave to the cochlea and is detected as audible sound [Lin and Wang, 2007]. However, there is no evidence that mobile phone-like RF-EMF exposure produces pulses of sufficient specific absorption to generate the microwave hearing effect, and we are not aware of any research conducted to determine whether it can explain the above changes to the human EEG. ...
Although there is consistent evidence that exposure to radiofrequency electromagnetic fields (RF‐EMF) increases the spontaneous resting alpha spectral power of the electroencephalogram (EEG), the reliability of this evidence is uncertain as some studies have also failed to observe this effect. The present study aimed to determine whether the effect of RF‐EMF exposure on EEG alpha power depends on whether EEG is derived from eyes open or closed conditions and assessed earlier (<5‐min) versus later (>25‐min) in the exposure interval. Thirty‐six adults participated in three experimental sessions, each involving one exposure: “Sham,” “Low,” and “High” RF‐EMF corresponding to peak spatial specific absorption rates averaged over 10 g of 0, 1, and 2 W/kg, respectively. Resting EEG was recorded at baseline (no exposure), during, and after exposure. Alpha power increase was found to be greater for the eyes open than eyes closed EEG during both the High (P = 0.04) and Low (P = 0.04) RF‐EMF exposures. There was also a trend toward it being larger at the end, versus the start of the “High” 30‐min exposure (P < 0.01; eyes open condition). This suggests that the use of eyes closed conditions, and insufficient RF‐EMF exposure durations, are likely explanations for the failure of some studies to detect an RF‐EMF exposure‐related increase in alpha power, as such methodological choices decrease signal‐to‐noise ratios and increase type II error.
... People with normal hearing can perceive pulsed EMFs in the frequency range 200 MHz ÷ 6.5 GHz, also knows as microwave hearing effect [14,15]. Continuous exposure to such fields can be traumatic and should be avoided whenever possible. ...
... The resulting exposure to high-power pulsed RF radiation and associated microwave energy deposition in head tissues may not produce overt tissue heating, but could elicit sensitive biological responses. The prime examples include microwave-pulse-induced acoustic pressure waves in the head (microwave auditory eff ect) [6,7], and the startle refl ex and motor-reaction behaviors observed in laboratory animals [8][9][10]. Indeed, there may be similarities between these pulsed microwave-induced responses. ...
The US Defense Advanced Research Projects Agency (DARPA) announced in August 2020 a bidding for submission of innovative research proposals for concepts that would lead to better understanding of the Impact of Cockpit Electro-Magnetics on Aircrew Neurology (ICEMAN: "Iceman" also happens to be the call sign of a fighter pilot portrayed in the movie Top Gun). In its request for proposal (RFP) [1], DARPA stated that "Current cockpits are flooded with radiofrequency (RF) noise from on-board emissions, communication links, and navigation electronics, including strong electromagnetics (EM) fields from audio headsets and helmet tracking technologies."
... In addition, because the light adjustment of the Cry protein is variable and can change in 2 h even under weak irradiation [23], the differences for the sexes at each time interval can simply reflect the adjusting time of this protein or other unknown magnetic receptors. In addition, some other papers have reported that there is a phenomenon called microwave hearing in mammals [37]. As the sequence and function of Cry proteins seem to be shared with many living species, including insects and plants [36,38], the behavioral difference could be due to auditory perception, not visual. ...
The physiological and behavioral influences of 2.45 GHz microwaves on Drosophila melanogaster were examined. Standing waves transitioned into heat energy effectively when passing through the insect body. On the contrary, travelling waves did not transit into heat energy in the insect body. This indicated that there was no concern regarding the thermal effects of microwave irradiation for levels of daily usage. However, we detected genotoxicity and behavioral alterations associated with travelling wave irradiation, which can be attributed to the non-thermal effects of the waves. Electron spin resonance (ESR) revealed that fruit flies possessed paramagnetic substances in the body such as Fe3+, Cu2+, Mn2+, and organic radicals. The temperature dependent intensities of these paramagnetic substances indicated that females possessed more of the components susceptible to electromagnetic waves than males, and the behavioral tests supported the differences between the sexes.
... coagulation, evaporation, and charring would long have occurred, and also because of the simplified assumption of surface energy deposition), the extreme magnitude of these results shows that exposure conditions may occur for which the temperature increase cannot be considered safe. Also, the temperature increase rate (initially S tr /(ρ t c L) for a plane-wave with penetration depth L), could lead to thermoelastic effects [Lin and Wang, 2007;Elder and Chou, 2003]. ...
Both the current and newly proposed safety guidelines for local human exposure to millimeter‐wave frequencies aim at restricting the maximum local temperature increase in the skin to prevent tissue damage. In this study, we show that the application of the current and proposed limits for pulsed fields can lead to a temperature increase of 10°C for short pulses and frequencies between 6 and 30 GHz. We also show that the proposed averaging area of 4 cm2, that is greatly reduced compared with the current limits, does not prevent high‐temperature increases in the case of narrow beams. A realistic Gaussian beam profile with a 1 mm radius can result in a temperature increase about 10 times higher than the 0.4°C increase the same averaged power density would produce for a plane wave. In the case of pulsed narrow beams, the values for the time and spatial‐averaged power density allowed by the proposed new guidelines could result in extreme temperature increases.
... Limited work has been performed examining the use of microwaves to stimulate sound directly in a user [4,5]. However, the communication has been limited to barely audible clicks (no complex messages) due to the inefficiencies in the transmission through bone and tissue. ...
We describe a means of communication in which a user with no external receiver hears an audible audio message directed only at him/her. A laser transmits the message, which is encoded upon a modulated laser beam and sent directly to the receiver’s ear via the photoacoustic effect. A 1.9 μm thulium laser matched to an atmospheric water vapor absorption line is chosen to maximize sound pressure while maintaining eye-safe power densities. We examine the photoacoustic transfer function describing this generation of audible sound and the important operational parameters, such as laser spot size, and their impact on a working system.
... Microwave radiation is another possible source of the health effects [23]. Pulsed radio frequency energy can cause an auditory response within the human head due to the thermoelastic expansion of portions of the auditory apparatus [24]. However, a remaining question is whether microwaves could have produced the highpitched sounds recorded by the smartphone in the AP news video. ...
This paper analyzes how ultrasounds could have unintentionally led to the AP news recordings of metallic sounds heard by diplomats in Cuba. Beginning with screen shots of the acoustic spectral plots from the AP news, we reverse engineered ultrasonic signals that could lead to those outcomes as a result of intermodulation distortion with non-linearity in the acoustic transmission medium. We created a proof of concept ultrasonic device that amplitude modulates a signal over an inaudible ultrasonic carrier. When a second inaudible ultrasonic source interfered with the primary source, intermodulation distortion created audible byproducts that share spectral characteristics with audio from the AP news. Our conclusion is that if ultrasound played a role in harming diplomats in Cuba, then a plausible cause is intermodulation distortion between ultrasonic signals that unintentionally synthesize audible tones. In other words, acoustic interference without malicious intent to cause harm could have led to the audible sensations in Cuba.
... Lin et al. [156] subsequently reported quantitative investigation with realistic numerical models of humans and animals by the same approach as the Japanese study [155]. Those studies provided quantitative understanding of this phenomenon, which has been in some cases exaggerated for the problem of public phobia about microwave hazard. ...
Research works on bioelectromagnetics in Japan are reviewed with a focus on the efforts devoted to the issue of human protection from electromagnetic field (EMF) exposures. History of this issue in Japan is briefly reviewed first for all EMF spectra. Then research works on radiofrequency (RF) EMF are summarized in more detail. The RF studies reviewed are mainly conducted in the framework of research program by the Ministry of Internal Affairs and Communications (MIC) started in 1997. Because of this program, collaborations between biology/medicine and engineering have been promoted. The results consistently show no evidence against the safety of RF-EMF within the exposure levels of internationally accepted guidelines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
... An example of well-known mechanism is the microwave hearing effect due to high power pulse exposures. This effect is attributed to a thermo-elastic interaction in the auditory sensory structures of the brain (Chou et al 1985, Lin andWang 2007). ...
An in vivo setup for pulsed electric field exposure at 3 GHz is proposed and characterized in this work. The exposure system allows far field, whole-body exposure of six animals placed in Plexiglas cages with a circular antenna. Chronic exposures under 18 W incident average power (1-4 kW peak power) and acute exposures under 56 W incident average power (4.7 kW peak power) were considered. Numerical and experimental dosimetry of the setup allowed the accurate calculation of specific absorption rate (SAR) distributions under various exposure conditions. From rat model numerical simulations, the whole-body mean SAR values were 1.3 W kg(-1) under chronic exposures and 4.1 W kg(-1) under acute exposure. The brain-averaged SAR value was 1.8 W kg(-1) and 5.7 W kg(-1) under chronic and acute exposure, respectively. Under acute exposure conditions, a 10 g specific absorption of 1.8 ± 1.1 mJ · kg(-1) value was obtained. With temperature rises below 0.8 °C, as measured or simulated on a gel phantom under typical in vivo exposures, this exposure system provides adequate conditions for in vivo experimental investigations under non-thermal conditions.
... In contrast to UMTS, GSM technology uses " pulsed " signals (1/8 duty factor). At 13 W/kg, while the steady-state temperature is unlikely to differ between GSM-1800 and UMTS, it is conceivable that the threshold for thermoelastic waves for the rat (ca. 1 mJ/kg) is reached for each of the GSM-1800 pulses (Lin and Wang, 2007). In humans at least, the numerical computation had provided the values of 2.63 kW/m 2 and 80 W/kg for the peak incident power density and peak SAR, respectively, to reach the 20 mPa auditory sound pressure threshold at the cochlea for a 20-ms pulse at 915 MHz. ...
After an indication of the numerous interveners who participated to this expertise study, and a presentation of the context, objective and methodology of this expertise, this report, based on a very large bibliography, discusses the various aspects of the '5G' deployment and the associated public controversy: situation of the deployment in France and abroad, problems raised, actors involved in the controversy, media content, health framework, and posture of the academic community. It describes international institutional positions with respect to health effects of the '5G' (by international bodies, foreign national institutions, and in the USA, Australia and New-Zealand, and Europe). In the next part, exposure data related to the '5G' are reported and compared: normative and regulatory framework, technological evolutions regrading the 5G bandwidth, assessment of the exposure level in the lower bandwidths. By referring to various public or scientific publications from different countries, it proposes a rather detailed overview of health effects related to the studied exposure (comments about scientific knowledge and acknowledgement, the different biological effects on the human body). Some recommendations, notably regarding the deployment of '5G', are finally presented. A second document presents the opinion of the ANSES (the French Agency for health safety) about the content of this report.
Presented are design considerations for a potential detection and measurement technique that could provide operational awareness of high power microwave (HPM) directed energy weapon exposure for force health protection applications, leveraging thermoacoustic (TA) wave generation as the field interaction mechanism. The HPM electromagnetic frequency (EMF) regime, used in applications in both the counter-materiel and non-lethal counter-personnel design space, presents real-time personnel exposure warning challenges due to the potentially wide variation in time and frequency domain characteristics of the incident beam. As with other EM-thermal interactions, the thermoacoustic wave effect provides the potential to determine EM energy and power deposition without the need to measure ambient field intensity values or overload-sensitive EMF survey equipment. Following measurement of relevant EM, thermal, and elastic material property values, a carbon-filled polytetrafluoroethylene (CF-PTFE) lossy dielectric medium subject to pulsed HPM was computationally modeled using the commercial finite element method multi-physics simulation software package COMSOL. The simulation was used to explore the impacts of various material properties on TA signal output as a function of simulated incident field power density, EM frequency, and pulse length, thereby informing the selection of system components for the further development of a full TA-based HPM detection chain.
For the past few weeks, media outlets have been reporting on the US State Department’s disclosure that Havana-based US diplomats were experiencing health issues [1-5]. Their residences were described to have been targeted with bursts of sound waves. Diplomatic staff and family members have repeatedly reported hearing loud buzzing or scraping sounds. Symptoms included severe hearing loss, headaches, ringing in the ears, nausea, and problems with balance or vertigo, which are suggestive of a connection to the inner-ear apparatus within the human head.
Over the past four or five years, nearly 200 US personnel have reported similarly mysterious attacks while working in places such as Havana, Guangzhou, London, Moscow, Vienna, and Washington, DC. It seems that every few months if not weeks, another mysterious attack on US diplomatic and intelligence personnel is reported, some as recent as July 2021 [1-3], The acute symptoms include headache and nausea, immediately following the hearing of loud buzzing or bursts of sounds. The illness and symptoms have been called the Havana Syndrome, after the city where cases were first reported. This refers to the range of symptoms first experienced by US State Department personnel stationed at the American embassy in Havana, Cuba.
This chapter explores where and how the microwave auditory effect or microwave induced thermoelastic wave phenomenon may be applied for practical purposes in life science, medicine, and other realms of human endeavors. An interesting and potentially significant diagnostic imaging applications of the microwave thermoelastic pressure wave interaction and some applied aspects of the microwave auditory effects are described. They include a discussion on early and current investigations of microwave thermoacoustic tomography (MTT) imaging and some applied aspects of the microwave auditory effects such as the recently reported covert personnel attacks at some diplomatic missions and the startle reaction from a sudden unexpected microwave auditory stimulus potentially causing the aircraft pilot to experience spatial disorientation during flight.
This chapter presents computer simulations of the thermoelastic pressure waves generated in anatomical human heads and whole-body models exposed to pulsed RF and microwave radiation by applying the numerical FDTD formulation. More precise descriptions of specific features and accurate information on the acoustic pressure waves generated inside the head and sound perceived by human observers are obtained. Computational simulations are examined for thermoelastic pressure waves generated in anatomic models exposed to near-zone sources and far-zone plane waves ranging in RF and microwave frequencies from 40 MHz to 3 GHz. It also includes anatomic head models exposed to localized 300- and 400-MHz magnetic resonance imaging (MRI) coil antennas driven by rectangular RF pulses.
This chapter presents rigorous multidisciplinary, mathematical analyses of the thermoelastic pressure wave generated in spherical human and animal heads exposed to pulsed microwave radiation. The results include dependence of induced sound pressure frequency and strength on microwave pulse characteristics. It provides information on the attributes of sound wave generated in the head as perceived by humans. It summarizes the first mathematical models for analyzing the sound pressure waves inside the head due to a microwave pulse and generalizations of the methodology to arbitrary SAR patterns of spherical symmetry. It also includes comparisons of predicted and measured response characteristics in human and animal heads.
Every few months, if not weeks, another mysterious attack on U.S. diplomatic and intelligence personnel is reported. Some of the attacks occurred years ago, while others were recounted as recently as July 2021
[1]
–
[3]
. Over the past four or five years, nearly 200 U.S. personnel have reported similar attacks while working in places like Havana, Guangzhou, London, Moscow, Vienna, and Washington, D.C. The acute symptoms include headache and nausea immediately following the sounds of loud buzzing or bursts. The illness and symptoms have been called the “Havana Syndrome” after the place where cases were first reported. It refers to the range of symptoms first experienced by U.S. State Department personnel overseas.
Reports on the U.S. Defense Advanced Research Projects Agency's Impact of Cockpit Electro-Magnetics on Aircrew Neurology (ICEMAN) project.
Presents the results of the U.S. National Academies of Sciences, Engineering, and Medicine (NASEM) report, “An Assessment of Illness in U.S. Government Employees and Their Families at Overseas Embassies." it is almost exactly three years since the publication of my article “Strange Reports of Weaponized Sound in Cuba” [2]. There, it was first hypothesized that “[a]ssuming that the reported events are reliable, there is actually a scientific explanation for the source of sonic energy. It could well be from a targeted beam of high-power microwave pulse radiation” [2]. In examining plausible causes of the described illnesses, the NASEM report makes that point that, among the mechanisms the study committee considered, the most plausible mechanism to explain these cases, especially in individuals with distinct early symptoms, appears to be directed, pulsed RF (microwave) energy.
Biological effects caused by a nanosecond pulse, such as cell membrane permeabilization, peripheral nerve excitation and cell blebbing, can be reduced or cancelled by applying another pulse of reversed polarity. Depending on the degree of cancellation, the pulse interval of these two pulses can be as long as dozens of microseconds. The cancellation effect diminishes as the pulse duration increases. To study the cancellation effect and potentially utilize it in electrotherapy, nanosecond bipolar pulse generators must be made available. An overview of the generators is given in this paper. A pulse forming line (PFL) that is matched at one end and shorted at the other end allows a bipolar pulse to be produced, but no delay can be inserted between the phases. Another generator employs a combination of a resistor, an inductor and a capacitor to form an RLC resonant circuit so that a bipolar pulse with a decaying magnitude can be generated. A third generator is a converter, which converts an existing unipolar pulse to a bipolar pulse. This is done by inserting an inductor in a transmission line. The first phase of the bipolar pulse is provided by the unipolar pulse's rising phase. The second phase is formed during the fall time of the unipolar pulse, when the inductor, which was previously charged during the flat part of the unipolar pulse, discharges its current to the load. The fourth type of generator uses multiple MOSFET switches stacked to turn on a pre-charged, bipolar RC network. This approach is the most flexible in that it can generate multiphasic pulses that have different amplitudes, delays, and durations. However, it may not be suitable for producing short nanosecond pulses (<100 ns), whereas the PFL approach and the RLC approach with gas switches are used for this range. Thus, each generator has its own advantages and applicable range.
In late August 2017, media out lets began reporting on the U.S. State Department's disclosure that Havana-based U. S. diplomats were experiencing health issues [1]-[5]. Their residences were described as having been targeted with bursts of sound waves. Diplomat ic staff and family members have repeatedly reported hearing loud buzzing or scraping sounds. Symptoms include severe hearing loss, headaches, ringing in the ears, nausea, and problems with balance or vertigo, which are suggestive of a connection to the inner ear apparatus within the human head.
This chapter provides an overview of the aspects of sound perception that have been explored by researchers in recent history. The outer ear channels acoustic energy to the middle ear, which channels transduced mechanical energy to the inner ear, which in turn transduces mechanical into electrical energy before it is sent through the auditory nerve to the brain for processing. The method of sound energy transduction is the most efficient method by which sound is perceived; however, there are several other documented ways in which sound energy can be sensed by the brain. These are bone conduction, cartilage conduction, tinnitus, and electromagnetic hearing. In addition to diseases of the auditory system, there is a segment of the population that is hypersensitive to sound and electromagnetic fields, which can have debilitating effects. These are briefly discussed in the chapter.
A spoken dialogue system as an automaton transforms an input message into an output message. Herein I propose wireless, receiverless communication technologies with the application of the microwave auditory effect as an output interface of the spoken dialogue system. The innovative interface produces intense psychological impacts on uninformed users. Elements of the proposed dialogue system and the wireless communication technologies reduce to a variety of disciplines, and any of the elements has its origin in the research and development in the national security during the World War II. Since the research concerning the national security tends to be classified for a long period of time, the hypothesis is proposed that the spoken dialogue system incorporating the output interface herein has been used in clandestine operations by military intelligence communities so as to induce psychosis such as schizophrenia.
The science community is governed by the paradigm that we cannot hear radiofrequency. Although microwave is one form of radiofrequency, it has been repeatedly reported that pulse-modulated microwave induces auditory perception. Therefore, it is mandatory to overturn the obsolete paradigm that we cannot hear radiofrequency into the novel paradigm that we can hear radiofrequency. In light of the aforementioned perspective, here I review the phenomenon that microwave in a pulse waveform induces auditory perception, and propose a theoretical framework to unify the air conduction, bone conduction and microwave auditory effect.
The author discusses the reasons behind the phenomenon that many people around the world report hearing a mysterious hum as reported by M. Lallanilla ("Mysterious hum driving people crazy around the world," NBC News, 12 Dec 2015).
Discusses the possible origins of the so-called humming sound heard around the world by some people.As it happens, there was at least a theoretical breakthrough of sorts in 2015. The Independent (United Kingdom) reported in April 2015, "Scientists have confirmed the cause of a strange humming noise that emanates from the Earth and has baffled people for more than forty years???and was even a factor in one reported suicide???However, the search for the truth could now be over because researchers claim that microseismic activity from long ocean that makes our planet vibrate and produces the droning sound. The pressure of the waves on the seafloor generates seismic waves that cause the Earth to oscillate." Examines this phenomenon.
In this issues Education Corner article, Rob Maaskant and Andreas Ros??n from Chalmers
University in Sweden present an analytical solution for a problem with educational
value in electromagnetic theory. With increasing reliance on computational tools in our
discipline, it is important to retain the ability to develop and use these kinds of techniques.
Lead author Maaskant is an expert in the development of highly advanced integral
equation-based analysis methods, which lends credibility to the arguments in the
article on the value of analytical methods in teaching and learning electromagnetics.
During the last decade, European methodologies on electromagnetic field measurement and human exposure assessment have been extensively developed and improved. At present, there is a large number of complex technical standards dedicated to various exposure situations. The implementation of the new methodology in the national practice might be difficult, expensive and time consuming. Taking into account the methodological change, we analyzed some practical difficulties that might occur and we emphasised some other limitations that might alter the quality of measurements. In this paper the authors propose a strategy based on a specific methodological approach and administrative measures to reduce implementation difficulties and to improve the quality of electromagnetic field measurements. Some simplified methods for checking compliance of complex electromagnetic environments with the requirements of exposure standards are proposed and the opportunity of using alternative methods is discussed.
The aim of this paper is to present the results of a study concerning nervous system and neuroendocrine effects in humans exposed to microwaves in occupational settings. In order to define exposure, microwave measurements and exposure metrics calculations were carried out and, consequently, a complex clinical epidemiological study has been done. Nervous system was studied both at peripheral and at central level by anamnesis, clinical examinations, electro-neurophysiological methods, questionnaires and psychological tests. Specific endocrinologic investigations, including hormone levels assessment were aimed to substantiate neuroendocrine effects. The results were statistically and epidemiologically analyzed in order to demonstrate the causality relationship presumed by study hypothesis. Microwave exposed subjects (electronic maintenance workers) had peripheral nervous system symptoms and related electromyography changes, central nervous system symptoms, related electroencephalography and psychological changes as well as neuroendocrine effects, especially calcium phosphorus balance changes and signs of thyroid dysfunction. There were significant differences versus matched controls as well as relevant associations with exposure metrics. Such changes put in evidence possible and plausible biological effects of microwaves on some structures of nervous system and point to the exposure metrics as important clues in the assessment of such effects. Authors consider that such studies have to be continued because the results have implications in understanding the intimate mechanisms of interaction between microwaves and nervous system. This kind of studies could facilitate the refinement of exposure standards, a step in the process of protecting the health of occupational exposed personnel.
The pressure waves developing at the cochlea by the irradiation of the body with a plane wave microwave pulse are obtained by numerical simulation, employing a two-step finite-difference time-domain (FDTD) algorithm. First, the specific absorption rate (SAR) distribution is obtained by solving the Maxwell equations on a FDTD grid. Second, the temperature rise due to this SAR distribution is used to formulate the thermoelastic equations of motion, which are discretized and solved by the FDTD method. The calculations are performed for anatomically based full body human models, as well as for a head model. The dependence of the pressure amplitude at the cochlea on the frequency, the direction of propagation, and the polarization of the incident electromagnetic radiation, as well as on the pulse width, was investigated. Bioelectromagnetics 35:XX–XX, 2014. © 2014 Wiley Periodicals, Inc.
Health protection against microwave exposure is regulated by exposure standards that set limits on exposure levels and by technical standards that provide guidance for field level measurement and human exposure assessment. Present international standards focus only on thermal and auditory effects of microwaves and, consequently, they show some lack of provisions for some practical exposure situations. On the other hand, studies on human exposure to pulsed microwaves require a complex exposure assessment, especially in the case of microwaves emitted by radar equipments. This work investigated the relevance of some parameters of pulsed microwaves that might be useful to correlate with specific health findings in microwave exposure studies. Proposed parameters were used for exposure evaluation of radar mechanics and engineers from a Romanian aircraft factory. Assessment of long-term, low-level exposure to radar fields was based on power density measurements. Besides computation of specific absorption rate, assessment of pulsed microwave exposure also included computation of some additional dosimetric and radiometric quantities. The majority values of mean power density and of specific absorption rate were below exposure limits confirming the lack of thermal effect. On the other hand, other quantities like peak power density frequently exceeded the reference level and were correlated with nervous system effects. Consequently, proposed additional quantities might be useful for emphasising dose-effect relationship when non-thermal effects of pulsed microwaves occur.
The focus of this journal is ¿wireless communications¿ which is presumed to use radio spectrum. But for the purpose of regulation, what are the upper and lower limits of that spectrum? An International Telecommunications Union publication addresses part of this question as follows From a technical viewpoint, the radio spectrum is the portion of the electromagnetic spectrum that carries radio waves. The boundaries of the radio spectrum are defined by the frequencies of the transmitted signals, and are usually considered to range from 9 kHz (kilohertz; thousand cycles per second) to 3000 GHz (gigahertz; billion cycles per second). The key characteristics of the spectrum are the propagation features and the amount of information which signals can carry. In general, signals sent using higher frequencies reach shorter distances but have a higher information-carrying capacity. These physical characteristics of the spectrum limit the currently identified range of applications for which any particular frequency band is suitable.
Oscillations at 50 kHz have been recorded from the round window of guinea pigs during irradiation by 918-MHz pulsed microwaves. The oscillations promptly follow the stimulas, outlast it by about 200 musec and measure to 50 muV in amplitude. They precede the auditory nerve's response and disappear with death. They are interpreted to be a cochlear microphonic and hence to demonstrate that the microwave auditory effect, in the guinea pig at least, is accompanied by a mechanical disturbance of the hari cells of the cochlea.
In recent years it has been recognized that low-power-density modulated RF energy can affect the functioning of higher living organisms. In this paper the sparse data generated in the western hemisphere on this subject are considered, the reasons for their sparseness are noted, and the hypotheses on mechanisms that may provide an explanation for the observed effects and other possible effects are sketched. Possible conclusions with regard to hazards to personnel are then considered.
This paper presents a numerical analysis of the thermoelastic waves excited by the absorbed energy of pulsed microwaves in a human head. First, the authors calculate the distribution of the specific absorption rate using a conventional finite-difference time-domain (FDTD) algorithm for the Maxwell's equation. They then calculate the elastic waves excited by the absorbed microwave energy. The FDTD method is again applied to solve the elastic-wave equations. The validity of the analysis for elastic waves is confirmed through comparison of the FDTD results with the analytical solutions in a sphere model. Two anatomically based human head models are employed for numerical calculations. The waveforms of the calculated pressure waves are different from the previously reported ones. It is especially shown that the surface heating is important in exciting the fundamental mode of the pressure waves in the head. The pulsewidth dependency of the loudness of microwave hearing is clearly explained by the simulation with realistic head models. The peak pressure of elastic waves in the realistic head models is of the same order as the previously reported values obtained with a homogeneous sphere model. The strength of elastic wave is discussed in consideration of the safety of this phenomenon.
The microwave auditory effect has been widely recognized as one of the most interesting and significant biological phenomena from microwave exposure. The hearing of pulsed microwaves is a unique exception to the airborne or bone-conducted sound energy, normally encountered in human auditory perception. This chapter describes the research studies leading to scientific documentation that absorption of a single microwave pulse impinging on the head may be perceived as an acoustic zip, click, or knocking sound, depending on the incident microwave power. A train of microwave pulses to the head may be sensed as an audible buzz, chirp, or tone by humans. It discusses the neurophysiological, psychophysical, and behavioral observations from laboratory studies involving humans and animals as subjects. The objective is to present what is scientifically known about the microwave auditory effect.
This is the third volume in the series, in which the topic of the effects of radio frequencies on human tissue, now increasingly a concern with the prevalence of cell phones, is explored by Prof. Lin and other researchers. The impact of electromagnetics on imaging and cardiology, both very keen areas of research at present, is also explored.
This paper demonstrates that pulsed microwave-evoked brainstem responses closely resemble those evoked by acoustic clicks in cats. Auditory evoked potentials to microwave pulses are recorded from the vertex and brainstem nuclei. At a fixed peak power and pulse width, the amplitude of vertex potentials decreases with increasing pulse repetition frequency. Reducing the stimulus intensity (peak power) while holding constant pulse width and rate is accompanied by a reduction in all of the vertex wave amplitudes. Increasing the pulse width increases the size of the vertex waves to a plateau with possible subsequent oscillations. Successive coagulative lesion of the inferior colliculus, lateral lemniscus and superior olive produced characteristic changes in the evoked potential wave forms, suggesting the possibility of using microwave pulses to achieve an estimate of sensori-neural involvement in the objective evaluation of hearing and to assess the presence of space-occupying lesions in patients with neurological disorders.
Several investigators have reported that high‐intensity, bone‐conducted sounds in the ultrasonic region above 20 kc/sec can produce auditory sensations in individuals with normal hearing. The present study was performed to establish the curve of audibility for bone conduction from approximately 5 to 100 kc/sec in a group of subjects with no audiometric or otological abnormalities. Fifty‐three male and 50 female subjects, ranging in age from 17 to 24 years, were tested on the left or right ear only by a modified method of limits, with all tests being conducted in an anechoic chamber. A crystal transducer, calibrated in a water medium, was used to transmit the acoustic energy to the mastoid portion of the temporal bone. For 38 male and 37 female subjects screened from the larger sample by means of an otological examination and an air‐conduction audiometric test from 250 cps to 8 kc/sec, the curve for the mean threshold of hearing showed a very sharp rise between 10 and 20 kc/sec with a slope of approximately 50 dB/octave, and a gradual rise from 20 to 100 kc/sec with a slope of approximately 15 dB/octave. The maximal discrepancy between men and women was approximately 5.5 dB (at 14 kc/sec). The standard deviations ranged from approximately 2 to 15 dB, with the maximal value for each group occurring at 16 kc/sec. In general, the results of the present study are in agreement with earlier fragmentary reports.
Microwave pulse-evoked potentials at the vertex show a series of waves
occurring in the first 10 ms following delivery of the pulse. The
sources of these waves, as in the case of acoustic click-evoked
responses, are action potentials generated in the cochlea and auditory
brain stem nuclei. We shall show, using microwave-induced auditory brain
stem responses, that the experimentally observed characteristics agree
with previously derived theoretical predictions in regard to pulse width
and frequency of impinging microwaves, pattern of absorbed microwave
energy, frequency of vibration, and threshold of sensation.
Rectangularly pulsed, 800-MHz microwaves were coupled via waveguide from
a 500-W source to the parietal area of the head of normal human
observers (Os). Pulse widths from 5 to 150 μS and pulse-repetition
rates (PRRs) from 50 to 20,000 pulses per second (pps) were employed.
Sine-wave audio-frequency (AF) signals could be presented alternately to
or concurrently with microwave pulses (RF signal) under conditions in
which O could adjust the amplitude, frequency and phase of the AF
signal. By matching timbre and loudness of the perceived RF and AF
signals during a succession of psychophysical measures—some while
O's head was being immersed in water—the Os yielded the following
results: (1) Both loudness and perceptual thresholds of the RF signal
were biphasic functions of pulse width and of PRR; (2) When pulse widths
increased toward 100 μs, some subjects perceived a different sound
that was lower in pitch and was referred externally to the head; (3) By
appropriate phasing of AF and RF signals after matching for pitch and
timbre, loudness of the RF signal could be reduced below the threshold
of perception; and (4) Extent of immersion of the head in water was
correlated with reduced loudness of the RF signal. Some of the data are
interpreted as posing explanatory difficulties for an exclusively
ther-moelastic mechanism of RF hearing.
Previously developed thermoelastic models of microwave-induced auditory
sensations are applied to calculate the frequency and amplitude of the
acoustic signals that are generated in human beings and laboratory
animals. Graphs of computed displacement and pressure as a function of
time are presented for several species.
This paper presents direct measurements of acoustic pressure wave propagation in cat brains irradiated with pulsed 2.45-GHz microwaves. Short rectangular microwave pulses (2 μs, 15 kW peak power) were applied singly through a direct-contact applicator located at the occipital pole of a cat's head. Acoustic pressure waves were detected by using a small hydrophone transducer, which was inserted stereotaxically into the brain of an anesthetized animal through a matrix of holes drilled on the skull. The measurements clearly indicate that pulsed microwaves induce acoustic pressure waves which propagate with an acoustic wave velocity of 1523 m/s.
The contribution of the ossicles (middle-ear bones) to auditory perception of microwaves was evaluated by the brain-stem evoked response (BER). Amplitude and latency of BERs were recorded from guinea pigs that were stimulated at various intensities by acoustic pulses coupled to the auditory canal or via bone conduction, and by microwave pulses. Blocking of the external ear, middle-ear damping, and middle-ear destruction produced little change in the BERs that were elicited by microwave pulses. Results indicate that activity in the central auditory pathway as induced by pulsed microwaves only requires stimulation of the cochlea. Conduction of pressure waves through the bones of the calvarium appears to be the mechanism responsible in perception of pulsed microwaves.
Rectangular pulse-modulated microwave radiation has been shown to produce auditory responses in mammals. It is therefore reasonable to explore the possibility of using microwave pulses to achieve an estimate of sensori-neural involvement in the objective evaluation of human hearing and to assess the presence of tumors or brainstem lesions in patients with neurological disorders. In this paper we shall show that microwave-evoked auditory response of cats closely resembles that evoked by acoustic pulse. We shall also give preliminary results obtained from electrodes fastened to the vertex of the skull after successive coagulative production of lesions in the inferior colliculus, lateral lemniscus, and superior olivary nucleus.
Pulsed microwaves impinging on the head of animals and man produce auditory sensations. Theoretical analyses indicate a series of resonant frequencies occurring inside the head. This is supported by previous observations of characteristic oscillations recorded from the round window of mammals during pulsed microwave irradiation.
When human subjects are irradiated with pulse modulated microwave energy they report the perception of a sound that appears to originate from within or slightly behing the head. Three of the possible mechanisms are examined using first order mathematical approximations and several simplifying assumptions. The results show that while all three (radiation pressure, strictive force and thermal expansion) are capable of producing the phenomenon, the stress resulting from thermal expansion may be so great that it masks the effect of the others completely.
The threshold conditions for an auditory perception of pulsed radiofrequency (RF) energy absorption in the human head have been studied on six volunteers with RF coils for magnetic resonance (MR) imaging. For homogeneous RF exposure with MR head coils in the 2.4-to 170-MHz range and pulse widths 3 μs, ⩽ Tp < 100 μs, the auditory thresholds were observed at 16 ± 4 mJ pulse energy. Localized RF exposure with optimized surface coils positioned flush with the ear lowers the auditory threshold to only 3 ± 0.6 mJ. The hearing threshold of RF pulses with Tp > 200 μs occurs at more or less constant peak power levels of typically 150 ± 50 W for head coils and as low as 20 W for surface coils. The results from this study confirm theoretical predictions from a thermoeleastic expansion model and compare well with reported thresholds from near field antenna measurements at 425 to 3000 MHz. Details of the threshold dependence on RF pulse length reveal primary sites of RF to acoustic energy conversion at the mastoid and temporal bone region and the outer layer of the brain from where thermoelastically generated pressure transients excite audible pressure waves at the resonance modes of the skull around 1.7 kHz and of the brain around 11 kHz. If not masked by usually dominating noise from switched gradients, the conditions for hearing RF pulses, as applied to head coils in MR studies with flip angle α at main field Bo, is given by Tp/ms ⩽ 0.4 (α/π)Bo/[T]. At peak power levels up to 15 kW presently available in clinical MR systems, there is no evidence known for detrimental health effects arising from the RF auditory phenomenon which is a secondary cause associated with primary RF to thermal energy conversion in body tissues. To avoid the RF-evoked sound pressure levels in the head rising above the discomfort threshold at 110 dB SPL, an upper limit of 30 kW applied peak pulse power is suggested for head coils and 6 kW for surface coils.
A psychophysical study of the perception of "sound" induced by illumination with pulse-modulated, ultrahigh-frequency electromagnetic energy indicated that perception was primarily dependent upon peak power and secondarily dependent upon pulse width. The average power did not significantly affect perception. Perceived characteristics of pitch and timbre appeared to be functions of modulation.
Acoustic transients can be thermally generated in water by pulsed microwave energy. The peak pressure level of these transients, measured within the audible frequency band as a function of the microwave pulse parameters, is adequate to explain the "clicks" heard by people exposed to microwave radiation.
Nine cats were prepared for the recording of potentials in 3 brain sites evoked by acoustic and microwave stimuli. Loci in which potentials were observed were eighth cranial nerve, medial geniculate nucleus and primary auditory cortex. The effect of cochlear disablement on these potentials was evaluated.Potentials at all sites were abolished by cochlear damage. There were no differences between acoustic and microwave stimuli in this regard. Data are interpreted as supporting the contention that the microwave auditory effect is mediated at the periphery as are the effects of conventional acoustic stimuli.
The intent of this paper is to bring a new phenomenon to the attention of physiologists. Using extremely low average power densities of electromagnetic energy, the perception of sounds was induced in normal and deaf humans. The effect was induced several hundred feet from the antenna the instant the transmitter was turned on, and is a function of carrier frequency and modulation. Attempts were made to match the sounds induced by electromagnetic energy and acoustic energy. The closest match occurred when the acoustic amplifier was driven by the rf transmitter's modulator. Peak power density is a critical factor and, with acoustic noise of approximately 80 db, a peak power density of approximately 275 mw/ cm ² is needed to induce the perception at carrier frequencies of 425 mc and 1,310 mc. The average power density can be at least as low as 400 μw/cm ² . The evidence for the various possible sites of the electromagnetic energy sensor are discussed and locations peripheral to the cochlea are ruled out.
This d'Arsonval Medal acceptance presentation highlights several research themes selected from Dr. Lin's published works, focusing on the microwave portion of the nonionizing electromagnetic spectrum. The topics discussed include investigation of microwave effects on the spontaneous action potentials and membrane resistance of isolated snail neurons, effects on the permeability of blood brain barriers in rats, the phenomenon and interaction mechanism for the microwave auditory effect (the hearing of microwave pulses by animals and humans), the development of miniature catheter antennas for microwave interstitial hyperthermia treatment of cancer, the application of transcatheter microwave ablation for treatment of cardiac arrhythmias, and the use of noninvasive wireless technology for sensing of human vital signs and blood pressure pulse waves. The paper concludes with some observations on research and other endeavors in the interdisciplinary field of bioelectromagnetics.
Microwave-induced acoustic pressures in the spherical models of human and animal heads are measured using a small hydrophone transducer. The measured acoustic frequencies that correspond to mechanical resonance of the head model agree with those predicted by the thermoelastic theory of interaction. Further, a three-pulse burst applied at the appropriate pulse repetition frequencies could effectively drive the model to respond in such a manner that the microwave-induced pressure amplitude would be increased by threefold or more.
Auditory signals generated in humans and animals who are irradiated with short rectangular pulses of microwave energy have been studied. Assuming that the effect arises from sound waves generated in the tissues of the head by rapid, thermal expansion caused by microwave absorption, and using a technique described previously, the governing equations are solved for a homogeneous spherical model of the head under constrained-surface conditions. The results indicate that the frequency of the auditory signal is a function of the size and acoustic property of the head only. While the amplitude and frequency of the microwave-induced sound are higher than those predicted by the stress-free boundary condition formulation, they are compatible with the experimental results reported to date.
When a human subject is exposed to pulsed microwave radiation, an audible sound occurs which appears to originate from within or immediately behind the head. Laboratory studies have also indicated that evoked auditory activities may be recorded from cats, chinchillas, and guinea pigs. Using a spherical model of the head, this paper analyzes a process by which microwave energy may cause the observed effect. The problem is formulated in terms of thermoelasticity theory in which the absorbed microwave energy represents the volume heat source which depends on both space and time. The inhomogeneous thermoplastic motion equation is solved for the acoustic wave parameters under stress-free surface conditions using boundary value technique and Duhamel's theorem. Numerical results show that the predicted frequencies of vibration and threshold pressure amplitude agree reasonably well with experimental findings.
A study of the effects of 3.0 GHz microwave pulses on the auditory systems of a number of mammalian species was conducted. Some human subjects heard a distinct "click" when irradiated with a sufficiently intense individual microwave pulse. Microwave induced auditory evoked responses were measured in the cat, dog, and chinchilia. The microwave peak power density levels at the threshold of producing an auditory response were determined for a number of human subjects in addition to the smaller animals. The inability of some of the human subjects to bear short microwave pulses was correlated with hearing losses above 8 kHz in frequency.
A microwave-induced thermoelastic pressure wave method for imaging of biological tissues has been investigated. Liquid-filled test tubes inside a water tank were used as phantom models. A pulsed 2.45 GHz microwave source and a hydrophone transducer were used to generate and to detect thermoelastic pressure waves. A pattern extraction algorithm was used to analyze the wave contours. Preliminary results show that the thermoelastic waveform is proportional to the size of the test tube and depends on the type of solution within the test tube. Two test objects can be detected with a spatial resolution better than 1 cm. These results suggest that a microwave-induced thermoelastic pressure wave system may provide valuable information for imaging tissue absorption and thermal expansion properties.
This paper presents direct measurements of acoustic pressure waves in brains of rats, cats, and guinea pigs irradiated with pulsed 2.450 and 5.655 GHz microwaves. A smal disk hydrophone transducer was surgically implanted in brains of anesthetized animals. Rectangular pulses (3 kW peak, 2.5 and 5.5 , us wide at 2.450 GHz and 200 kW peak, 0.5 ¿s wide at 5.655 GHz) were applied through horns, waveguides, and direct contact antennas. The results clearly indicate that pulsed microwaves induce acoustic pressure waves in the brain, confirming earlier theoretical predictions. Furthermore, hydrophone output waveforms and on-line analyzed spectra show that fundamental and second harmonics were nearly identical to those predicted by the thermoelastic theory. However, the hydrophone records show complex sequences of higher order vibrational modes which deviate from predictions based on a homogeneous spherical model of the head.
When human subjects are exposed to rectangular pulses of microwave radiation, an audible sound occurs which appears to originate from within or behind the head. It has been shown that electrophysiological auditory activity may be elicited by exposing the brains of laboratory animals to rectangular pulses of microwave energy. These results suggest that a microwave auditory phenomenon is evoked by a mechanism similar to that responsible for conventional sound reception and that the primary site of interaction resides peripheral to the cochlea. A comparison of the pressure amplitudes, such as those produced in a homogeneous planar layer of brain matter that is irradiated by a microwave pulse, indicates that the peak pressure due to thermal expansion is much greater than either radiation pressure or electrostriction. Theoretical analyses for a spherical brain based on the thermoelastic mechanism of interaction were found to agree with experimentally observed characteristics and indicate also that the induced sound frequency is only a function of the size and acoustic property of the brain. A few suggestions have been made for future research aimed at furthering our knowledge on microwave auditory effect and its health implications.
Fundamentals and applied aspects of nonionizing radiation.
- Guy
Biological effects of electromagnetic waves, Vol I.
- Lin
Biological effects and medical applications of electromagnetic fields.
- Lin
Human auditory system response to pulsed radiofrequency energy in RF coils for magnetic resonance at 2.4 to 179 MHz.
- Roschmann
Biological effects of nonionizing radiation.
- Lin
RF thermoelastic pressures induced in a human head model in high-pass MRI birdcage coils.
- Lin