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.
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 .
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.
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 .
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