The Frey effect, also known as the microwave hearing effect, or the microwave hearing phenomenon, was first reported by persons working in the vicinity of radar transponders during WWII.
The Frey effect, was named after the american neuroscientist who first extensively studied its nature in the cold war era. This effect consists of audible clicks induced by pulsed modulatedmicrowave frequencies and generated directly inside the human head without the need of any receiving electronic device, sounds not audible by other nearby people.
This effect was later discovered to not being limited to the higher band of the electromagnetic spectrum, and even inducible with other carriers.
This constitutes the founding principle behind modern long range active invasive Brain Machine Interface .
In general, by scanning the full spectrum of the electromagnetic frequency , it appears that the shorter the wavelength, the higher the limit of resolution of the EMF carrier, thus allowing ever increased physiological effect in the exposed subject.
Starting with the well documented microwaves, where the effect is due to the induction of thermoelastic waves by radio frequencies pulses at a boundary between the tissues of dissimilar dielectric properties within the head, with propagation of the waves to the auditory system.
Then more interesting, the Infrared wavelengths are already short enough to allow the individual neuron discrimination, thus efficiently usable in the direct controlled neural firing process (Discover Magazine,November Edition 2004).
X-rays where known to induce visual effect since their discovery in 1895 as reported by G. Brandes in the form of an uniform blue-gray glow that might be explained today as the result of direct excitation of retinal nerve cells. These wavelengths might already allow the direct discrimination of individual synapses.
Gamma rays where first reported to cause visual perception of flashes of light during the Apollo program. Indeed, astronauts en route for the Moon where subject to cosmic rays bombardments, inducing some Cherenkov effect in the fluid of there eyeballs. It is no excluded that the same effect might occur when a gamma ray strikes a neuron or a synapse and inducing a photoelectric effect. In addition, gamma ray wavelengths might even allow the direct discrimination of individual neurotransmitters.
Other Possible Natural Carriers
Finally, atomic size carriers such as neutrinos, energetic particles originating outside of the Earth composing cosmic rays including electrons, protons, and atomic nuclei,
or fast moving alpha rays or beta rays might be neural firing capable through the Cherenkov effect. Their inherent smaller size allow of course an individual targeting of neurotransmitters.
Primary Cold War Era Research in the US
In the US, the first American to publish on the microwave hearing effect was Allan H. Frey as early as 1961.
The then experimental subjects were discovered to be able to actually hear appropriately pulsed microwaves, and from a distance of hundred of meters from the transmitter. But this was accompanied by side effects such as dizziness, headaches and a pins and needles sensation .
Sharp and Grove soon developed for the Advanced Research Projects Agency at Walter Reed Army Institute of Research , receiverless wireless voice transmission application, in 1975.
Peaceful Applications
Devices used for scaring birds away from aircraft near airfields by microwave hearing and induction of vertigo exist (Kreithen ML. Patent #5774088 “Method and system for warning birds of hazards” USPTO granted 6/30/98.).
But the majority of applications are dedicated for direct machine to brain wireless communication , with numerous patents.
Weaponization
It is alleged that researches where also conducted in the US to study its use in non-lethal weaponry.
While the USSR is supposed to have concentrated their effort in the microwave band of the spectrum, frequencies that can be easily thwarted with conventional EMF shielding like Faraday Cage or Tempest, it is highly suspected that the US might have explored and mastered more exotic, ground penetrating, metal penetrating long range carriers, possibly neutrinos or gamma rays, allowing by the same time the achievement of even higher limit of resolution .
Thijs VMJ. Application #WO1992NL0000216 “Hearing Aid Based on Microwaves” World Intellectual Property Organization Filed 1992-11-26, Published 1993-06-10.
Giori FA and Winterberger AR, “Remote Physiological Monitoring Using a Microwave Interferometer”, Biomed Sci Instr 3: 291-307, 1967.
Frey AH and Messenger R., "Human Perception of Illumination with Pulsed Ultrahigh-Frequency Electromagnetic Energy", Science 181: 356-8, 1973.
Rodwell R, defense correspondent report “Army tests new riot weapon”, New Scientist Sept. 20, p 684, 1973.
Guy, A.W., C.K. Chou, J.C. Lin and D. Christensen, 1975, Microwave induced acoustic effects in mammalian auditory systems and physical materials, Annals of New York Academy of Sciences, 247:194-218
Justesen DR, “Microwaves and Behavior”, Am Psychologist, 392(Mar): 391-401, 1975.
Michaelson SM, “Sensation and Perception of Microwave Energy”, In: Michaelson SM, Miller MW, Magin R, and Carstensen EL (eds.) Fundamental and Applied Aspects of Nonionizing Radiation Plenum Press, New York, p 213-24, 1975.
Eichert ES and Frey AH, “Human Auditory System Response to Lower Power Density Pulse Modulated Electromagnetic Energy: A Search for Mechanisms”, J Microwave Power 11(2): 141, 1976.
Bise W. “Low power radio-frequency and microwave effects on human electroencephalogram and behavior” Physiol Chem Phys 10(5): 387-98, 1978.
Lin JC, Microwave Auditory Effects and Applications, Thomas, Springfield Ill, p 176, 1978.
Stocklin PL and Stocklin BF, “Possible Microwave Mechanisms of the Mammalian Nervous System”, T-I-T J Life Sci 9: 29-51, 1979.
Frolich H, “The Biological Effects of Microwaves and Related Quiestions”, Adv Electonics Electron Physics 53: 85-152, 1980.
Lai H, “Neurological Effects of Radiofrequency Electromagnetic Radiation” In: Lin JC (ed.) Advances in Electromagnetic Fields in Living Systems vol 1, Plenum, N Y & London, p 27-80, 1994.
Beason RC and Semm P, “Responses of neurons to an amplitude modulated microwave stimulus”, Neurosci Lett 333: 175-78, 2002.
Elder JA and Chou CK, “Auditory Responses to Pulsed Radiofrequency Energy”, Bioelectromagnetics Suppl 8: S162-73, 2003.
Smith C, “On the Need for New Criteria of Diagnosis of Psychosis in the Light of Mind Invasive Technology”, J Psycho-Social Studies 2(2) #3, 2003.
McMurtrey JJ, “Microwave Bioeffect Congruence with Schizophrenia”, In press, 2003.
Thijs VMJ. Application #WO1992NL0000216 “Hearing Aid Based on Microwaves” World Intellectual Property Organization Filed 1992-11-26, Published 1993-06-10.
Assadullahi R and Pulvermuller F. “Neural Network Classification of Word Evoked Neuromagnetic Brain Activity” In: Wermter S, Austin J, and Willahaw D (eds.) Lecture Notes in Artificial Intelligence: Emergent Neurocomputational Architectures Based on Neuroscience Heidelberg Springer, p 311-20, 2001.