Microwave auditory effect

The microwave auditory effect or the Frey effect is an effect consisting in the auditory perception of microwave radiation. Perceived sounds occur directly inside the human skull without the use of additional electronic equipment.

For the first time, the effect was registered by people who worked near radars in the years The Second World War, and the sounds they perceived were not audible to others. During the Cold War, this phenomenon was explained by the American neurophysiologist Alan Frey — his work was published in the Journal of Applied Physiology in 1962.

As it turned out, when exposed to pulsed or modulated microwave radiation on the areas around the cochlea of the ear, it is absorbed by the tissues of the inner ear, accompanied by their thermal expansion. During this process, shock waves arise, perceived by a person as a sound that no one else can hear.

It was also found that with the appropriate choice of a modulating signal, it is possible to transmit information to a person in the form of individual words, phrases and other sounds. Depending on the radiation parameters, the sound created in the head can irritate, cause nausea and even disable. The volume of the perceived sound can be changed, but it is impossible to cause an acoustic injury, since the eardrum does not participate in the process in any way.