The Frey Effect: How Pulsed Microwaves Create Sound Inside the Skull
Allan Frey documented it in 1961. Sixty years of peer-reviewed research confirmed it. The microwave auditory effect is real — here is exactly how it works, what the threshold is, and what Lin (2022) actually says.
Published 2025-03-15
In 1961, Allan Frey stood more than a hundred feet from a radar antenna, far too distant to hear any acoustic sound, and heard clicking. Not from outside his ears — from inside his skull. He published this in Aerospace Medicine the same year. Sixty years of independent replication followed. The mechanism is now understood, the threshold is quantified, and the National Academies of Sciences cited it as the most plausible explanation for Havana Syndrome in their 2020 report. This is not a fringe claim. Here is exactly what the science says. How It Works: Thermoelastic Expansion The mechanism has a name: thermoelastic expansion . When pulsed microwave energy is absorbed by brain tissue, it causes a temperature rise of approximately 10⁻⁶ degrees Celsius per pulse — far too small to feel as heat. But the rise is fast — on the timescale of the pulse, typically 10–30 microseconds — and fast temperature changes cause mechanical stress. That stress launches a pressure wave through the skull. The wave travels through bone, arriving at the cochlea (inner ear) via bone conduction. The cochlea transduces it into electrical signals. The auditory nerve fires. The brain perceives a sound. The ears are completely bypassed. Blocking the ear canal, filling it with mineral oil, or wearing earplugs does not prevent the effect. Lin (2022) §V.G: "When the external auditory meatus of guinea pigs was blocked by cotton balls soaked in mineral oil, the microwave evoked BER potentials remained unaltered." The perceived frequency is determined not by the microwave carrier frequency but by the geometry…
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