Microwave auditory effect

The microwave auditory effect, also known as the microwave hearing effect or the Frey effect, consists of audible clicks induced by pulsed/modulated microwave frequencies that are generated directly inside the human head without the need of any receiving electronic device. The effect was first reported by persons working in the vicinity of radar transponders during World War II. These induced sounds are not audible to other people nearby. The microwave auditory effect was later discovered to be inducible with shorter-wavelength portions of the electromagnetic spectrum. During the Cold War era, the American neuroscientist Allan H. Frey studied this phenomenon and was the first to publish (Journal of Applied Physiology, Vol. 17, pages 689-692, 1962) information on the nature of the microwave auditory effect; this effect is therefore also known as the Frey effect.

Research by NASA in the 1970s showed that this effect occurs as a result of thermal expansion of parts of the human ear around the cochlea, even at low power density. Later, signal modulation was found to produce sounds or words that appeared to originate intracranially. It was studied for its possible use in communications but has not been developed due to the possible hazardous biological effects of microwave radiation. Similar research conducted in the USSR studied its use in non-lethal weaponry.

Natural sources of electromagnetic perception
For centuries, humans have reported hearing unexplained noises in conjunction with meteors including "thunder-like sounds" at the scene of the Tunguska event on June 30 1908. Astronomer Edmund Halley collected several such accounts after a widely-observed meteor burned up in the sky over England. The Leonid meteor shower in November 2001 also led to many reports of observers hearing crackling or fizzing noises. Similar observations have been reported by soldiers near the site of nuclear explosions.

Colin Keay, a physicist at the University of Newcastle in Australia, has advanced a hypothesis that purports to explain these phenomena. According to Keay's theory, meteor trails give off very low frequency (VLF) radio signals that the human ear cannot sense directly but are heard because a transducer on the ground must be converting the radio waves into sound waves. He has produced experiments that demonstrate that materials as commonplace as aluminum foil, thin wires, pine needles, and wire-framed glasses can act as suitable transducers.

Powerful VLF waves can induce physical vibrations in these objects, which are transmitted to the air as sound waves. Keay defines the field of geophysical electrophonics as "the production of audible noises of various kinds through direct conversion by transduction of very low frequency electromagnetic energy generated by a number of geophysical phenomena." Some scientists state that electrophonic effects may also be caused by lightning strikes, very bright auroras, and earthquakes.

Electroreception has also been studied in the animal world. Ritz et al., in "A Model for Photoreceptor-Based Magnetoreception in Birds", hypothesize that transduction of the Earth's geomagnetic field is responsible for the magnetoreception systems of birds. Specifically, they propose that this transduction may take place in a class of photoreceptors known as cryptochromes.

References:
 * "Listening to Leonids", NASA Science and Technology Directorate
 * Colin Keay's web site

Full spectrum electromagnetic perception
In general, there is scientific evidence that waves at different levels of the electromagnetic frequencies have physiological effects on people exposed to them, including auditory effects.


 * Infrared wavelengths can be used to control the neural firing. Research on rats has shown that infrared waves can trigger responses in specific muscles. (Discover Magazine,November Edition 2004).


 * X-rays can induce visual effects. This was discovered in 1895 as reported by G. Brandes who saw a uniform blue-gray glow that scientists say is likely the result of direct excitation of retinal nerve cells.


 * Gamma rays were first reported to cause visual perception of flashes of light during the Apollo program. Astronauts en route for the Moon were subject to cosmic rays bombardments, inducing some Cherenkov effect in the fluid of their eyeballs.

Primary Cold War-era research in the US
The first American to publish on the microwave hearing effect was Allan H. Frey, in 1961. In his experiments, the subjects were discovered to be able to hear appropriately pulsed microwave radiation, from a distance of 100 meters from the transmitter. This was accompanied by side effects such as dizziness, headaches, and a pins and needles sensation.

Sharp and Grove developed receiverless wireless voice transmission technologies for the Advanced Research Projects Agency at Walter Reed Army Institute of Research, in 1975.

Peaceful applications
Devices used for scaring birds away from aircraft near airfields by microwave hearing and induction of vertigo exist.

Patented applications

 * Flanagan GP. “Nervous System Excitation Device” USPTO granted 7/16/68.
 * Puharich HK and Lawrence JL. “Hearing systems” USPTO granted 12/21/71.
 * Malech RG. “Apparatus and method for remotely monitoring and altering brain waves” USPTO granted 4/20/76.
 * Stocklin PL. “Hearing device” USPTO granted 8/22/89.
 * Brunkan WB. “Hearing system” USPTO granted 10/31/89.
 * Thijs VMJ. Application #WO1992NL0000216  “Hearing Aid Based on Microwaves” World Intellectual Property Organization Filed 1992-11-26, Published 1993-06-10.
 * Mardirossian A. “Communication system and method including brain wave analysis and/or use of brain activity” USPTO granted 1/4/00.