Microwave auditory effect

The Frey effect (English microwave auditory effect, microwave hearing effect, RF hearing ) is a phenomenon that occurs in the vicinity of powerful sources of pulsed radio frequency radiation. Some people, it is possible pulsed high frequency without any additional aids ( such as radio receivers) perceive reproducible than clicking sounds.

A description of the effect was published by the American explorer Allan H. Frey from 1961 in several articles.

This phenomenon was discovered during the Second World War in people who were in the immediate vicinity of a powerful radar system.

Scientific Research Results

After publishing the first data on the Frey effect research has been done into the causes and effects of the phenomenon. Also possible applications were examined for communication.

The Frey effect is now considered a generally scientifically accepted phenomenon without pathological significance.

Persons, high-frequency radiation are for pulsed microwave or general sensitive, describe the noise that occurs as a very quiet clicking sounds that occur synchronously to radiation and are audible only in silence. While initially assumed that only the microwave radiation within the Frey effect is noticeable, is now known that the candidate frequency range depending on the source of 2.4 MHz to 10 GHz, or any other source of a plurality of 100 MHz up to some 10 GHz extends.

As a point of origin of the stimulus human cochlea ( snail) is assumed in the inner ear. According to the currently favored thermoelastic expansion theory it should come to small pulsed heat- induced expansion changes by thermoelastic waves scarf lead over bony structures to the inner ear. Direct interaction with the auditory nerve is excluded. From studies in healthy subjects who were exposed to RF fields in magnetic resonance imaging at the company Philips, a lower response in the range of 16 ± 4 mJ in the frequency range 2.4 MHz was determined to 170 MHz. When positioned over the ears, the threshold decreased to 3 ± 0.6 mJ. Depending on the coil used typically stimuli were determined for services between 20 and 150 (± 50) W. The most effective, the effect in the vicinity of the temporal bone could be achieved. From the inner ear from reaching the auditory pathway signals via the parent structures of the brain, just as it is also the case for purely acoustic signals initiated. The stimulus intensity is dependent on the energy of individual pulses. The frequency of the resulting aloud is independent of the high frequency used, but showing a dependency to the dimensions of the human skull.