When US diplomats based in Cuba reported that they had hearing loss as the result of hearing a strange noise, an investigation kicked off. It found that they had been exposed to 鈥渉ealth attacks鈥� by some kind of sonic device. Now it is being posited that the device used microwaves.
Those affected reported that the incidents earlier this year involved bursts of painful, highly localised sound at home or in hotel rooms. After-effects included headaches, nausea and hearing loss. Subsequent medical examination suggests that some of the victims have , which isn鈥檛 consistent with a sonic device, and which tends to rule out suggestions of hysteria.
Enter of the University of Illinois at Chicago, who reports that the localised sounds and corresponding health effects might both be the result of a beam of pulsed microwaves in which the microwaves are heard as sound. Lin has been working with this microwave auditory effect for decades, and describes it in relation to the Cuban events in a paper in the .
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Brain expansion
鈥淎 minuscule but rapid rise in tissue temperature, resulting from the absorption of pulsed microwave energy, creates a thermoelastic expansion of brain matter,鈥� says Lin. The resulting acoustic wave is perceived as sound.聽 The microwave beam might affect individuals indoors and could cause brain tissue damage from a combination of heating and shock waves.
In 2008, the Pentagon funded development of a 鈥渟ilent scream鈥� crowd-control device known as MEDUSA (Mob Excess Deterrent Using Silent Audio) which generated an uncomfortably loud microwave auditory effect. Lin is not aware of any existing device, but says development 鈥渋s always a possibility by some military-related organisations鈥�.
鈥淭hat theory is a real stretch,鈥� says of the University of Pennsylvania, who investigates the effects on the body of biomedical applications including microwaves. He says the peak power levels needed would involve a rather conspicuous transmitter.
鈥淚t would require something like a major airport radar transmitter with the subject鈥檚 head close to the antenna in its direct beam,鈥� says Foster.聽 鈥淚 guess it is possible, but not likely.鈥�
IEEE Microwave Magazine
